Merge branch 'master' of https://github.com/j6t/gitk

Merge branch 'master' of https://github.com/j6t/gitk

* 'master' of https://github.com/j6t/gitk:
  gitk: Mention globs in description of preference to hide custom refs
  gitk: filter invisible upstream refs from reference list
  gitk: avoid duplicated upstream refs
  gitk i18n: Remove the locations within the Bulgarian translation
  gitk i18n: Update Bulgarian translation (322t)
  gitk: allow Tcl/Tk 9.0+
  gitk: use -profile tcl8 on encoding conversions
  gitk: use -profile tcl8 for file input with Tcl 9
  gitk: Tcl9 doesn't expand ~, use $env(HOME)
  gitk: switch to -translation binary
  gitk: update scrolling for TclTk 8.7+ / TIP 474
  gitk: restore ui colors after cancelling config dialog
  gitk: set config dialog color swatches in one place
  gitk: Add user preference to hide specific references