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.

apply.c

@@ -437,6 +437,8 @@ static int parse_git_header(char *line, int len, unsigned int size, struct patch
 			{ "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 },