Added utility method next() that returns a Location adjacent to the current one based on the direction given.
Overloaded move() with one that takes a Direction instead of a Location.
Implemented its render() method.
Added two Zambies to the map as a test.
Added getTiles() method for iterating through all of the tiles.
Added a method for retrieving the fallback tile.
Updated to support the new map size (20x15). Also prevented the user from being table to select a tile outside of the tileset.
Changed the game window to 640x480. Added support in GameContainer for user-specified window widths and heights.
Merge pull request #8 from mfrancis95/mike

Window size change, Builder updates, and additional changes