Replace cute_c2.h with Box2C

[RandyGaul]

Box2C has refactored it's API to be simpler using structs and handles. The collision routines are easily accessible and callable without any setup or fuss. We should remove cute_c2.h and replace it with an out-of-the-box box2c integration. It would still be best to wrap all of the b2*** names with aliases/typedefs, and do minor cleanup inline wraps of certain functions.

It may be best to also replace the dynamic tree with Box2C's dynamic tree, perhaps also keeping the tree serialization code as an addon feature.

[RandyGaul]

https://github.com/erincatto/box2c

[RandyGaul]

Concerns

• Need to note about the MIT license