gitk: Add keybinding to switch to parent commit

Signed-off-by: Max Kirillov <max@max630.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
gitk: Updated Bulgarian translation (302t,0f,0u)

Signed-off-by: Alexander Shopov <ash@kambanaria.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Git 2.1-rc2

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'master' of git://ozlabs.org/~paulus/gitk

* 'master' of git://ozlabs.org/~paulus/gitk:
  gitk: Updated Bulgarian translation (302t,0f,0u)
  gitk: Add keybinding to switch to parent commit
config: teach "git -c" to recognize an empty string

In a config file, you can do:

  [foo]
  bar

to turn the "foo.bar" boolean flag on, and you can do:

  [foo]
  bar=

to set "foo.bar" to the empty string. However, git's "-c"
parameter treats both:

  git -c foo.bar

and

  git -c foo.bar=

as the boolean flag, and there is no way to set a variable
to the empty string. This patch enables the latter form to
do that.