Fixed tile-break glitch FOR REAL I SWEAR. Also new camera behaviour.

- fixed the tile breaking glitch (only occured when replacing tiles that you dug)
- camera doesn't center on player when it reaches edge of map (still buggy)
- added null check for getAdjacentTiles()
- more functional center() method for World (will soon make a Camera class)
- made diamond shovel 3.33333x more efficient temporarily (was testing tile breaking)
- removed tile light value