Added btGeneric6DofSpringConstraint, set/get breakingThrehsold to btTypedConstraint, btContactSolverInfo and two btWheelInfo attributes
Added btGeneric6DofSpringConstraint and linear/angular limits to btGeneric6DofConstraint.
btGeneric6DofConstraint implements btTypedConstraint
Added getNumConstraintRefs and getConstraintRef to btRigidBody, removeAction to btDynamicsWorld and getCurrentSpeedKmHour to btRaycastVehicle.
Added btGeneric6DofSpringConstraint and linear/angular limits to btGeneric6DofConstraint.
btGeneric6DofConstraint implements btTypedConstraint
Added btCollisionWorld::btGenerateInternalEdgeInfoAlias and btCollisionWorld::InterpolatedClosestRayResultCallback to Bullet, added the use of InterpolatedClosestRayResultCallback to btDefaultVehicleRaycaster::castRay. Added btCollisionWorld::btGenerateInternalEdgeInfoAlias and btTriangleInfoMap to ammo.idl.