Save current menu to temp variable when entering options from in-game

This is to pre-emptively prevent piling up stack frames for what I'll be
adding next, which is pressing Esc in the options menu in-game
automatically moving you back to MAPMODE.

desktop_version/src/Game.cpp

@@ -390,6 +390,7 @@ void Game::init(void)
     over30mode = false;
 
     ingame_titlemode = false;
+    kludge_ingametemp = Menu::mainmenu;
 
     /* Terry's Patrons... */
     const char* superpatrons_arr[] = {