Bullet debug draw added

It is off by default, see attributes of dSolverNode to turn it on

src/BulletDynamics/ConstraintSolver/btSliderConstraint.cpp

@@ -64,7 +64,7 @@ void btSliderConstraint::initParams()
 
 	m_useLinearReferenceFrameA = USE_OFFSET_FOR_CONSTANT_FRAME;
 
-
+	calculateTransforms(m_rbA.getCenterOfMassTransform(),m_rbB.getCenterOfMassTransform());
 }