Chest bugfix and Feature enhancement

This pull request overhauls the BlockChestTFC placement logic. The primary purpose is fixing Issue #536 which resulted in invalid double chests.

However, it also implements the logic required for chests of differing types to be adjacent. Before, two chests could be adjacent, but only 2. Now, the chests can be in arbitrary locations and the inventories and rendering are properly updated:

![2014-06-04_20 00 38](https://cloud.githubusercontent.com/assets/207428/3182188/d8813098-ec4c-11e3-88af-69213fb1a810.png)