BUG: Local edges where not updated in merge Patches
added parametric calculation point on arc when the arc is known
HexEdge control points are now moved when vertices change.

Beware that moving vertices through the vertice editor one at the time
will create an intermediate state, which will change the parameter t.
And hence the proximate move will be affected.

Moving all vertices at the same time works as expected.
BUG: edges are now redrawn when control points change
added image of calcParameterArc