Fix bug in Debug output from PGS solver.
Added new PointInPlaneWithStiction constraint as a more efficient replacement for the use of a PointInPlane constraint along with two NoSlip1D constraints in unilateral contact.
Changed PointPlaneContact to use the new PointInPlaneWithStiction constraint which simplifies the implementation and makes it faster. Created PointPlaneFrictionlessContact that uses the old PointInPlane constraint.
Modified RigidContact1 to use the PointPlaneFrictionlessContact element for the bouncing balls example.