The game has begun!
The game has begun!

This commit allows the user to start playing the 2048 game.
Simply start a board in irb:

  $> require './game'
  $> b = Board.new

Now you can use the methods display, up!, down!, right! and left! to
move your fields to either direction or display the field.

Changes:
- up! down! left! and right! permit to move the fields
- populate_nil! populates a number of nil fields on the board
  (handy when you finished sliding the fields together)
- display generates a simple output of the board
- moves Array Monkey-Patch to custom file to ninja's delight
- improves comments in general

tarnap/2048ai