Remove regen call from ReferencePoint.Point

This is a simple and obvious fix - properties should not have a regen side effect.  

Further, this regen call was introduced only for the case where a ReferencePoint is constructed on a Face.  I've moved the only regen call to the constructor where such a ReferencePoint is created, so it is invoked only once for such a reference point.  

@lukechurch, @ikeough