* Fixed a crash bug when freeing sprite resources.
 * Added a skeleton of a base class for objects.
Added a loader class which the program's execution starts in. From
here, need to make it query the user to load a game module, start up
the module,a nd create the game object, and then execute it. Thus the
main src/directory will become a program loader & API, and then, say, a
modules (or games) directory will become the main game source tree.
implement