New zone, sprite batching, layer support.

Sprite batching is in; this leads to faster rendering since we only do one call/layer.

We also support tiled layers (finally) and toggling them (this is a bit of a hack since it's for testing purposes only). 

New zone to demonstrate layers, hopefully this can replace the current zone #1 so we can start playing around with it.

Tiled files need to be adjusted somewhat. We need to come up with a way to do consistent metadata/layers (for collisions) -- right now, the only collision layer that we use is consistent no matter what the layer looks like.