Show actions in render display.

![robotgamegui](https://f.cloud.github.com/assets/2941863/1588660/57b68f3e-5256-11e3-82fd-21c6911cd977.gif)

* Shows letter representing action taken.
* Shows attack and move collision direction.
* Increases display size.
* Adds action tracking code to game.py.

Could be further optimised.