* plugins/gtk/st/Gtk.st (main): create a process that does nothing. It will be only...

	* plugins/gtk/st/Gtk.st (main): create a process that does nothing. It will be only used to hold signal callbacks and to keep the scheduler on

	* plugins/gtk/plugin-init.c (_syx_gtk_iteration): replaced _syx_gtk_main
	(syx_g_closure_marshal): do it without threads and in a single process
	(Gtk_main): register an idle and save the process where to put main loop callback executions
	(Gtk_mainQuit): register an idle and save the process where to put main loop callback executions

	* syx/syx-object.h (syx_semaphore_new): added