Sketcher BSplineInsertKnot

Description
Inserts a knot into an existing B-spline. If a knot already exists at the specified parameter, increases the multiplicity of that knot by one.

Usage

 * 1) Select a B-spline, then either:
 * 2) * Press the button.
 * 3) * Use the menu.
 * 4) Move the cursor to the desired location where the new knot point is to be created, and click to insert the knot. The parametric value of the knot is displayed for reference.
 * 5) Optionally repeat the step above to create more knots.
 * 6) Right click or press  to exit knot insertion mode.
 * 7) Optionally use Sketcher_BSplineIncreaseKnotMultiplicity.svg Increase knot multiplicity to increase the multiplicity of the knot(s).