Implementation one animation.

1. Example comes from the Qt tutorial: Animated Tiles Example
2. How it works:
	- Calculate the positions of each rectangle(item)
	- Move the item from the src_pos to dst_pos
	- Divide the move to N step. This is where the animation happened
		- How long one step is decided by the formula, like linear,
		quadratic, etc.

3. Referece: QEasingCurve::InQuad