- 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