Teach git-completion.bash how to complete git-merge.
Teach git-completion.bash how to complete git-merge.

Now that git-merge is high-level Porcelain users are going to expect
to be able to use it from the command line, in which case we really
should also be able to complete ref names as parameters.

I'm also including completion support for the merge strategies
that are supported by git-merge.sh, should the user wish to use a
different strategy than their default.

Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git