Maze gen

This adds a maze generator demo (openfl and js).
Might need some adjustments, but it's kind of hypnotic to play with it.

You can try the JS ver here: https://dl.dropboxusercontent.com/u/32864004/dev/FPDemo/maze-gen-js/GridMazeDemo.html

Press SPACE to generate a new maze, or ENTER to reset the entity.