diff: add --stat for diffstat output
diff/qdiff --stat invokes patch.diffstat() on the diff output.
When in interactive mode, the output's maximum width is determined by the
terminal's width.
% add file
adding qqq.txt
% commit first revision
% set bookmark
% commit second revision
% set bookmark
% update to -2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% commit new head
created new head
% bookmarks updated?
test 1:16b24da7e457
test2 1:16b24da7e457
% strip to revision 1
saving bundle to
saving bundle to
adding branch
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
% list bookmarks
* test 1:9f1b7e78eff8
* test2 1:9f1b7e78eff8