Deprecate gtk_main_*, gtk_dialog_run().

Submitted by Allison (desrt)

Description

The whole concept of multi-level recursive Gtk mainloops is a bit odd. They're mostly used for modal dialogs via gtk_dialog_run(), which we've sort of discouraged people from using for a long time.

Time for formal deprecations, I think.

The best replacement would be GtkApplication, of course. For those who don't want to go that route, they can easily emulate the non-recursive case of gtk_main()/gtk_main_quit() by using a global GMainLoop variable and g_main_loop_run()/g_main_loop_quit().

Version: 3.91.x