+ fix minor error
Bez Curve mockup using bSpline tools.

Add Edit functionality to mockup
fix Close button for BexCurve Edit
fix tracker behaviour in for BezCurve.undoLast
Draft beziers: Split poles to multiple bezier segments

Draft set degree of bezier curve
Close Draft bezier curves
implement addPoint for piecewise Bezier curves
use circle trackers for control points
prepare functions to make bezier knots tangent or symmetric