Add commitdiff between commit and each of it's parent

A link is added next to each parent of a commit, leading to the new
diff-functionality in ui-diff.c.

Also added support for a path-parameter to filelevel diffs accessed via the
diffstat.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/cgit.c b/cgit.c
index aee7ba3..3d85a08 100644
--- a/cgit.c
+++ b/cgit.c
@@ -116,7 +116,7 @@
 	} else if (!strcmp(cgit_query_page, "view")) {
 		cgit_print_view(cgit_query_sha1, cgit_query_path);
 	} else if (!strcmp(cgit_query_page, "diff")) {
-		cgit_print_diff(cgit_query_sha1, cgit_query_sha2);
+		cgit_print_diff(cgit_query_sha1, cgit_query_sha2, cgit_query_path);
 	} else {
 		cgit_print_error("Invalid request");
 	}