sameDirection = function(direction, center1, center2){
				switch(direction){
					case "t": return Math.abs(center1.x - center2.x) < 2 && center1.y < center2.y
					case "r": return center1.x > center2.x && Math.abs(center1.y - center2.y) < 2
					case "b": return Math.abs(center1.x - center2.x) < 2 && center1.y > center2.y
					case "l": return center1.x < center2.x && Math.abs(center1.y - center2.y) < 2
					default: return false;
				}
			}
Return a true if the center 1 is in the same direction than center 2
@param {Object} direction
@param {Object} center1
@param {Object} center2