Blender Git Loki

BGE: Add missing documentation and attribute constraint_type for ConstraintWrapper

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