Update Box2D to v2.3.0
Fix renamed member variable of b2PolygonShape
Add additional interface for Box2D v2.3.0
Merge branch 'master' into v2.3.0
Add introducion information
Fix a reference Issue
remove "GetNext" method, return std::vector instead
Merge branch 'master' into v2.3.0
Stable branch 2.2.2
Remove a redefined b2ContactList
GetWorld() now return the same python object and fix the indexing issue
Fix unexpected error occurs if a error raised from a virtual function
Remove some unnecessary inline declaration to optimize the binary size.