1. Add attribute to get the constraint type.
2. Add missing documentation for getParent, setParam, constraint_id in bge.types.KX_ConstraintWrapper.rst.
3. Add missing documentation for GENERIC_6DOF_CONSTRAINT and flag bit in bge.constraints.rst.
4. Fix typo in CcdPhysicsEnvironment.cpp
Reviewers: moguri
Reviewed By: moguri
Differential Revision: https://developer.blender.org/D654