ZENGINE: Create the concept of a working window

The working window is a Rect centered inside the actual window edges. All in-game
coordinates are in the working window coordinate system. Also, all images in-game
are clipped to the edges of the working window.
ZENGINE: Implement ZENGINE::getCursorManager()
ZENGINE: Fix header #defines to match their file names
ZENGINE: Set the initial game location (The opening video and menu)
ZENGINE: Slight function name change to increase clarity
ZENGINE: Add panning support
ZENGINE: Clip coords outside the working window
ZENGINE: Add background image wrapping

There is still a discontinuity when wrapping, but I am committing so that
others can look at the code
ZENGINE: Add cursor and background image resets during location change
ZENGINE: Add _renderManager::update() to ZEngene::run()