Merge branch 'ab/mktag'

Merge branch 'ab/mktag'

"git mktag" validates its input using its own rules before writing
a tag object---it has been updated to share the logic with "git
fsck".

* ab/mktag: (23 commits)
  mktag: add a --[no-]strict option
  mktag: mark strings for translation
  mktag: convert to parse-options
  mktag: allow omitting the header/body \n separator
  mktag: allow turning off fsck.extraHeaderEntry
  fsck: make fsck_config() re-usable
  mktag: use fsck instead of custom verify_tag()
  mktag: use puts(str) instead of printf("%s\n", str)
  mktag: remove redundant braces in one-line body "if"
  mktag: use default strbuf_read() hint
  mktag tests: test verify_object() with replaced objects
  mktag tests: improve verify_object() test coverage
  mktag tests: test "hash-object" compatibility
  mktag tests: stress test whitespace handling
  mktag tests: run "fsck" after creating "mytag"
  mktag tests: don't create "mytag" twice
  mktag tests: don't redirect stderr to a file needlessly
  mktag tests: remove needless SHA-1 hardcoding
  mktag tests: use "test_commit" helper
  mktag tests: don't needlessly use a subshell
  ...