Improve file dialogs

- Fixes #314
- Adds file extensions to sound and image browsing
- Some options no longer default to our config dir
- Always add a shortcut to our config dir
- Remove broken 'last_dir' functionality, gtk already knows recent

src/fe-gtk/urlgrab.c

@@ -146,7 +146,7 @@ static void
 url_button_save (void)
 {
 	gtkutil_file_req (_("Select an output filename"),
-							url_save_callback, NULL, get_xdir (), NULL, FRF_WRITE|FRF_FILTERISINITIAL);
+							url_save_callback, NULL, NULL, NULL, FRF_WRITE);
 }
 
 void