CCApplication: GameExit deterministic disposal or graphics resources

* proposed fix for #100
* we explicitly call graphDev.Dispose to ensure graphics resources are Disposed of before any finalisers are called

src/platform/CCApplication.cs

@@ -706,6 +706,10 @@ void GameDeactivated(object sender, EventArgs e)
 
         void GameExiting(object sender, EventArgs e)
         {
+            // Explicitly dispose of graphics device which will in turn dispose of all graphics resources
+            // This allows us to delete things in a deterministic manner without relying on finalizers
+            xnaGame.GraphicsDevice.Dispose();
+
             foreach (CCWindow window in gameWindows)
             {
                 window.EndAllSceneDirectors();

src/platform/CCDrawManager.cs

@@ -1394,7 +1394,6 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposing)
             {
-                ReinitResource();
                 isDisposed = true;
             }
         }