Our blame viewer has had a very fancy progress bar at the bottom of
the window that shows the current status of the blame engine, which
includes the number of lines completed as both a text and a graphical
meter. I want to reuse this meter system in other places, such as
during a branch switch where read-tree -v can give us a progress
meter for any long-running operation.
This change extracts the code and refactors it as a widget that we
can take advantage of in locations other than in the blame viewer.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
b29bd5ca3b