plugin.h & lua add playlist_insert_playlist

having issues running lua and loading a playlist

Change-Id: I72d32d77e6567ceed7e8e5fd492eebf0ee44561a

apps/plugin.c

@@ -803,6 +803,7 @@ static const struct plugin_api rockbox_api = {
     /* new stuff at the end, sort into place next time
        the API gets incompatible */
     warn_on_pl_erase,
+    playlist_insert_playlist,
 };
 
 static int plugin_buffer_handle;