Changes:
-Added support for custom inertia and center of mass in 3D
-Added support for custom center of mass in 2D
-Calculated center of mass from shapes in 2D (same as in 3D)
-Fixed mass properties calculation with disabled shapes in 2D/3D
-Removed first_integration which is not used in 2D and doesn't seem to
make a lot of sense (prevents omit_force_integration to work during the
first frame)
-Support for custom inertia on different axes for RigidBody3D
82ea2a7045