Merge branch 'g4w-gitk' of https://github.com/dscho/gitk

* 'g4w-gitk' of https://github.com/dscho/gitk:
  gitk: make the "list references" default window width wider
  gitk: fix arrow keys in input fields with Tcl/Tk >= 8.6
  gitk: Use an external icon file on Windows
  gitk: Unicode file name support
  gitk(Windows): avoid inadvertently calling executables in the worktree

Signed-off-by: Johannes Sixt <j6t@kdbg.org>