In repositories with lots of remotes, looking at the history in gitk
can be borderline insane with all the red labels for remote refs.
Introduce a new option in the preferences that makes gitk ignore
remote refs entirely, so they don't take up space in the display.
Wished-for-by: Thell Fowler <tbfowler4@gmail.com> Signed-off-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Paul Mackerras <paulus@samba.org>