fix(compat): handle and warn config.optionMergeStrategies

release: v3.1.0-beta.1

build: fix compat build type treatment

chore: document ts and alt strategy for compat build

chore: migration build docs [ci skip]

fix(reactivity): fix tracking for readonly + reactive Map (#3604)

fix #3602

fix(hydration): fix update before async component is hydrated (#3563)

fix #3560

fix(Teleport): avoid changing the reference of vnode.dynamicChildren (#3642)

fix #3641

fix(runtime-core): watching multiple sources: computed (#3066)

fix #3068

feat: onServerPrefetch (#3070)

Support equivalent of `serverPrefetch` option via Composition API.

chore: update build status badge [ci skip]

ci: move to github actions / remove circleci config

ci: improve transition tests ci stability

ci: test github actions

chore: bump more

chore: bump transition test duration on CI

chore: remove markdown spec debounce assertion for ci stability

build(deps-dev): bump @types/node from 14.14.43 to 14.14.44 (#3734)

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 14.14.43 to 14.14.44.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build(deps-dev): bump vite from 2.1.5 to 2.2.4 (#3733)

Bumps [vite](https://github.com/vitejs/vite/tree/HEAD/packages/vite) from 2.1.5 to 2.2.4.
- [Release notes](https://github.com/vitejs/vite/releases)
- [Changelog](https://github.com/vitejs/vite/blob/main/packages/vite/CHANGELOG.md)
- [Commits](https://github.com/vitejs/vite/commits/v2.2.4/packages/vite)

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build(deps): bump @babel/types from 7.13.13 to 7.14.0 (#3714)

Bumps [@babel/types](https://github.com/babel/babel/tree/HEAD/packages/babel-types) from 7.13.13 to 7.14.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.14.0/packages/babel-types)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps-dev): bump typescript from 4.2.3 to 4.2.4 (#3710)

Bumps [typescript](https://github.com/Microsoft/TypeScript) from 4.2.3 to 4.2.4.
- [Release notes](https://github.com/Microsoft/TypeScript/releases)
- [Commits](https://github.com/Microsoft/TypeScript/compare/v4.2.3...v4.2.4)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps-dev): bump @vitejs/plugin-vue from 1.2.0 to 1.2.2 (#3708)

Bumps [@vitejs/plugin-vue](https://github.com/vitejs/vite/tree/HEAD/packages/plugin-vue) from 1.2.0 to 1.2.2.
- [Release notes](https://github.com/vitejs/vite/releases)
- [Changelog](https://github.com/vitejs/vite/blob/main/packages/plugin-vue/CHANGELOG.md)
- [Commits](https://github.com/vitejs/vite/commits/plugin-vue@1.2.2/packages/plugin-vue)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps): bump @babel/parser from 7.13.12 to 7.14.0 (#3707)

Bumps [@babel/parser](https://github.com/babel/babel/tree/HEAD/packages/babel-parser) from 7.13.12 to 7.14.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/main/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/commits/v7.14.0/packages/babel-parser)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps-dev): bump ts-jest from 26.5.4 to 26.5.5 (#3706)

Bumps [ts-jest](https://github.com/kulshekhar/ts-jest) from 26.5.4 to 26.5.5.
- [Release notes](https://github.com/kulshekhar/ts-jest/releases)
- [Changelog](https://github.com/kulshekhar/ts-jest/blob/master/CHANGELOG.md)
- [Commits](https://github.com/kulshekhar/ts-jest/compare/v26.5.4...v26.5.5)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Upgrade to GitHub-native Dependabot (#3694)

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps): bump postcss-selector-parser from 6.0.4 to 6.0.5 (#3705)

Bumps [postcss-selector-parser](https://github.com/postcss/postcss-selector-parser) from 6.0.4 to 6.0.5.
- [Release notes](https://github.com/postcss/postcss-selector-parser/releases)
- [Changelog](https://github.com/postcss/postcss-selector-parser/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss-selector-parser/compare/v6.0.4...v6.0.5)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

build(deps): bump postcss from 8.2.6 to 8.2.13 (#3704)

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.6 to 8.2.13.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.2.6...8.2.13)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

chore: bump e2e test debounce

wip: make legacy global apis available on app instance as well

wip: fix v3 render fn detection regex

wip: defineReactive on instance with keys starting with $

wip: allow compatConfig mode to be a function

fix(hmr): don't remove __file key from component type

wip: expose configureCompat via named export

wip: make singleton mutations affect all app instances

wip: only generate non-scope slot flag when compatConfig is present

wip: remove v-if key warning as there are legit use cases

wip: relay compiler-core warnings in compiler-sfc with codeframe

wip: exclude legacy slots from $scopedSlots

wip: fix compiler dep externalization

wip: more private properties

wip: enable private vnode properties even for built-ins

wip: fix native template compat

wip: root instance $destroy before $mount

wip: vm._data for vuex compat

build(deps-dev): bump sass from 1.32.8 to 1.32.12

Bumps [sass](https://github.com/sass/dart-sass) from 1.32.8 to 1.32.12.
- [Release notes](https://github.com/sass/dart-sass/releases)
- [Changelog](https://github.com/sass/dart-sass/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sass/dart-sass/compare/1.32.8...1.32.12)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build(deps-dev): bump codemirror from 5.60.0 to 5.61.0

Bumps [codemirror](https://github.com/codemirror/CodeMirror) from 5.60.0 to 5.61.0.
- [Release notes](https://github.com/codemirror/CodeMirror/releases)
- [Changelog](https://github.com/codemirror/CodeMirror/blob/master/CHANGELOG.md)
- [Commits](https://github.com/codemirror/CodeMirror/compare/5.60.0...5.61.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build(deps-dev): bump chalk from 4.1.0 to 4.1.1

Bumps [chalk](https://github.com/chalk/chalk) from 4.1.0 to 4.1.1.
- [Release notes](https://github.com/chalk/chalk/releases)
- [Commits](https://github.com/chalk/chalk/compare/v4.1.0...v4.1.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build(deps-dev): bump @types/node from 14.14.36 to 14.14.43

Bumps [@types/node](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/node) from 14.14.36 to 14.14.43.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/node)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

build(deps-dev): bump eslint from 7.22.0 to 7.25.0

Bumps [eslint](https://github.com/eslint/eslint) from 7.22.0 to 7.25.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v7.22.0...v7.25.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

chore: ignore compat entries for coverage

wip: compat test coverage

wip: test for global filter registration

wip: tests for compiler compat

wip: move compat test cases + filter tests

wip: test for v-model compat

wip: test for legacy component compat

wip: more tests for v2 compat

wip: test for instance and options compat

wip: fix isCustomElement

chore: Merge branch 'v2-compat'

wip: tests for global config compat

feat: support component-level `compilerOptions` when using runtime compiler

- The `delimiters` component option is deprecated.
  Use `compilerOptions.delimiters` instead.

fix(compiler-core): preserve comment content in production when comments option is enabled

chore: update IE11 support [ci skip]

wip: tests for global api compat

wip: ref v-for compat

wip: fix tests

wip: whitespace behavior compat

feat(config): support configuring runtime compiler via `app.config.compilerOptions`

- `config.isCustomElement` is deprecated - use `app.config.compilerOptions.isCustomElement` instead.

refactor(compiler): improve whitespace: 'preserve' behavior from #1600

- discard leading/ending whitespace inside an element
- condense preserved whitesapce into single space

feat(compiler-core): whitespace handling strategy

chore: fix typo in assertion

feat(devtools): improved KeepAlive support

This change allows the devtools to access the cached vnodes from the KeepAlive component in order to display them as inactive in the components tree

wip: add private api compat flag

wip: more compat tweaks

wip: more compat tweaks

wip: more compat tweaks

wip: class/style fallthrough compat

wip: treat compat model listener as already declared

perf: only trigger $attrs update when it has actually changed

chore: include component info in recursive update warning

wip: more compat progress

fix(watch): avoid traversing non-plain objects

wip: compat integration progress

chore: adjust the parameter order of the mountChildren function

wip: filters compat

wip: warn against `<template functional>`

wip: inline-template compat

wip: refactor

wip: plain template tag compat

perf(compiler): skip unncessary checks when parsing end tag

wip: warn v-bind object ordering

wip: remove unncessary deprecation messages

wip: default mode for compat build

wip: compiler should default to v3 behavior

wip: warn key usage of v-if branches

wip: warn v-if/v-for co-usage

wip: v-bind.sync compat

wip: invert compiler compat behavior default during tests