Revert "研究一下box2d的碰撞处理"

This reverts commit fd984a589e3fed7eddd48ec7c29ba61e01a7541b.
Revert "碰撞后的状态的几种处理方式待考量"

This reverts commit 1b3916e8ad87163fff90ba1693bccdc540f4a374.