Prototype git commit viewer

[Paul Mackerras <paulus@samba.org>]

Over the weekend I hacked up a prototype viewer for git commits in
Tk.  It's called gitk and is at:

	http://ozlabs.org/~paulus/gitk

(that's the actual script itself :).

It displays a window with two panes; the upper one shows a summary of
all the commits with a graph on the left showing the relationship of
the commits (each dot represents a commit, with lines joining parents
and children).  The list is displayed with the most recent commit at
the top, and parents below their children.

If you click on a commit, the bottom pane shows more details of the
commit including the commit comments.

I plan to add a pane to show the list of files changed by the commit,
and provide a way to pop up a dirdiff-style diff viewer window to view
the actual diffs.  I also plan to add a way to view the diffs between
arbitrary points in the graph using girdiff.  There is quite a lot of
UI tweaking to be done too.  However, it's already quite useful in its
current state.

Paul.