Added a resources folder with a test tileset.
Added TileSet class for managing textures.
Tileset is now implemented as a HashMap of tiles.
Added equals() method to Location for hashing purposes.
GridMap now contains a HashMap of tiles in addition to entities. The tiles are represented as their coordinates in the tileset instead of the actual images.
getTile() uses a Location to query the tile instead of separate x and y parameters. This makes calls from GridMap.getTile() easier to make.
Added a Tileset test to the game. Randomly generates tiles to use at the start of the program.
Added support for setting the tileSize in the constructor.
Tileset now has a "fallback" black tile that it'll return when trying to access a tile that doesn't exist.
Whoops. Forgot to make the fallback tile have the same tileSize.
Merge pull request #3 from mfrancis95/mike

Tileset additions