PhysicsBody allows the user to create bodies with complicated shapes and simplifies image drawing into it.
Constructor has seven parameters:
- instance of PhysicsWorld
- shape of body (instance of b2CircleShape or b2PolygonShape)
- image which may be drawn into body
- body type
- density
- friction
- bounce
All the parameters are required.
The class has almost all functions and properties from native b2Body.