Rename Grid to Board
Add H2048.Game

Along with a randomTile function.
Add clean target to make
Add randomEmptyIndex function
Add randomEmptyPoint function
Add canShift/canMove functions
Add isOver function
Add addRandomTile function
Return maybes from randomEmpty* functions
Add addRandomTiles function
Add H2048.Settings
Use tabs to separate tiles
Add new function
Add H2048.Main

I feel like I'm missing something with getMove. I want it to stop
reading input if a character doesn't match. That way you won't have to
input three characters to have it return Nothing.
Fix getMove

It will now fail fast. This feels gross, though.