diff 'rename' format change.

Clearly even Junio felt git "rename" header lines should say "from/to"
instead of "old/new", since he wrote the documentation that way.

This way it also matches "copy".

git-apply will accept both versions, at least for a while.
diff --git a/apply.c b/apply.c
index ec63a0c..1f48ef9 100644
--- a/apply.c
+++ b/apply.c
@@ -437,6 +437,8 @@
 			{ "copy to ", gitdiff_copydst },
 			{ "rename old ", gitdiff_renamesrc },
 			{ "rename new ", gitdiff_renamedst },
+			{ "rename from ", gitdiff_renamesrc },
+			{ "rename to ", gitdiff_renamedst },
 			{ "similarity index ", gitdiff_similarity },
 			{ "dissimilarity index ", gitdiff_dissimilarity },
 			{ "", gitdiff_unrecognized },