Modeling Data - try to make the base surface C1 when creating offset surface

Sometimes the offset surface is created on top of a B-Spline surface that does not pass the check for C1-continuity, though it is smooth enough in all knots. The matter is that it has multiplicity in some knots equal to degree.

It is proposed to try to copy the base surface and call RemoveKnot() with tolerance equal to Precision::Confusion(). If it performs well then modified surface will not differ from the original geometrically, but becomes C1-continuous.