When there is a large number of new or modified files,
"display_all_files" takes a long time, and git-gui appears to hang.
This change limits the number of files that are displayed. This
limit can be set as gui.maxfilesdisplayed, and is 5000 by default.
A warning is shown the first time the list of files is truncated
in this GUI session. Subsequent truncations are not mentioned to
the user.
Signed-off-by: Dan Zwell <dzwell@zwell.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>