Simplify the plug-in query API and fix plugin-browser

- remove the menu path and image types from "gimp-plugins-query",
  they are available via GimpProcedure, also reorder and rename
  its remaining return values to make sense
- remove the "menu_path" parameter to gimp_proc_view_new(),
  it can also ask GimpProcedure
- adapt plugin-browser to the new API and make it use GimpProcedure
- fix plugin-browser's tree view to show all menu hierarchies
  completely, it was still expecting menu paths that contain
  the menu label too

libgimp/gimpprocbrowserdialog.c

@@ -330,7 +330,7 @@ browser_selection_changed (GtkTreeSelection      *sel,
                           -1);
 
       gimp_browser_set_widget (GIMP_BROWSER (dialog->priv->browser),
-                               gimp_proc_view_new (proc_name, NULL));
+                               gimp_proc_view_new (proc_name));
 
       g_free (proc_name);
     }