Add ball
Introduce variable radius
Add plate
Modify Plate to follow the mouse pointer
Add SectorBlock
Add GameObject, GameObjectManager

Ball, Block, Plate implement GameObject.
Add GameObjectManager.get
Change plate rectangle to sector
Modify SectorBlock to use GraphicsUtils
Add reflection feather
Modify Plate.width
Fix bug
Add package objects
Refactor collision

Add Collision, CollisionResult.
Add Ball.getPrevX, getPrevY.
Add collision of ball and block
Add further remove block

Add GameObject.isRemoval
Modify GameObjectManager.updateAll
Refactor Ball
Fix collision