Refactor: Moved App_ChangeGame() to DoomsdayApp

DoomsdayApp::changeGame() is now responsible for directing the
game changing operation. Also moved a bunch of file loading routines
that handle the loading of a game's files when the game is loaded.

doomsday/apps/client/include/dd_main.h

@@ -50,11 +50,6 @@ void DD_FinishInitializationAfterWindowReady();
 
 void DD_ConsoleRegister();
 
-/**
- * Returns @c true if shutdown is in progress.
- */
-bool DD_IsShuttingDown();
-
 /**
  * Print an error message and quit.
  */
@@ -89,10 +84,7 @@ void DD_UpdateEngineState();
 // Game modules -------------------------------------------------------------------
 //
 
-/**
- * Switch to/activate the specified game.
- */
-bool App_ChangeGame(Game &game, bool allowReload = false);
+int DD_ActivateGameWorker(void *context);
 
 /**
  * Returns the application's global Games (collection).

doomsday/apps/client/src/clientapp.cpp

@@ -787,6 +787,8 @@ void ClientApp::unloadGame(Game const &upcomingGame)
 
     R_InitViewWindow();
     R_InitSvgs();
+
+    Map::initDummies();
 }
 
 void ClientApp::makeGameCurrent(Game &newGame)