v0.1.4-ALPHA

Added another dimension to TileState array. When referring to
TileState(0,x,y) then I'm referring to the current TileStates, and when
referring to TileState(1,x,y) then I'm referring to the previous
TileStates, those from which I undo. This allows implementation of
Practice GameMode, which features undo-ing your last move.