added snapshot filename to the link

 - changed cgit_pageurl into cgit_fileurl with the filename parameter
 - rewritten cgit_pageurl as a wrapper around cgit_fileurl

Signed-off-by: Michael Krelin <hacker@klever.net>
diff --git a/cgit.h b/cgit.h
index 6937c42..aabf725 100644
--- a/cgit.h
+++ b/cgit.h
@@ -201,6 +201,8 @@
 extern int cache_expired(struct cacheitem *item);
 
 extern char *cgit_repourl(const char *reponame);
+extern char *cgit_fileurl(const char *reponame, const char *pagename,
+			  const char *filename, const char *query);
 extern char *cgit_pageurl(const char *reponame, const char *pagename,
 			  const char *query);