built-in diff.

This starts to replace the shell script version of "git diff".

Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -46,6 +46,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "log", cmd_log },
 		{ "whatchanged", cmd_whatchanged },
 		{ "show", cmd_show },
+		{ "diffn", cmd_diff },
 	};
 	int i;