contrib/subtree updates, but here are only the ones that looked
ready. The remainder of the patches will have another day.
* dg/subtree-fixes:
contrib/subtree: make the manual directory if needed
contrib/subtree: honor DESTDIR
contrib/subtree: fix synopsis
contrib/subtree: better error handling for 'subtree add'
contrib/subtree: use %B for split subject/body
contrib/subtree: remove test number comments
Fix the documentation of add to show that a repository can be
specified along with a commit.
Suggested by Yann Dirson <dirson@bertin.fr>.
Signed-off-by: David A. Greene <greened@obbligato.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
