Fixed play_controller not joining current event context

Was broken when I moved the GUI2 drawing trigger code to global scope probably.

src/play_controller.cpp

@@ -176,6 +176,8 @@ play_controller::play_controller(const config& level, saved_game& state_of_game,
 
 	persist_.start_transaction();
 
+	join();
+
 	game_config::add_color_info(level);
 	hotkey::deactivate_all_scopes();
 	hotkey::set_scope_active(hotkey::SCOPE_GAME);