Part: GeomBSpline extension for basic BSPline Sketcher support

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1) Basic set/get interface for poles, weights, knots and multiplicities

2) Introduction of GeomBoundedCurve class replicating OCC hierarchy. Why? To provide seamless start/end point interface for any bounded curve, i.e. Bezier, BSpline,

Note: The ArcOfConic start/end point interface relies on GeomTrimmedCurve, and introduces CCW/CW correcting code which relies on Axis. Axis are introduced in GeomConic and are
not part of GeomBounded.

Note 2: In the future, it may be thought to make GeomArcOfConic (the equivalent of GeomTrimmedCurve) deriving from GeomBoundedCurve, as to fully replicate OCC hierarchy. GeomBoundedCurve
defines the functions as virtual to allow seamless integration.

src/Mod/Part/App/AppPart.cpp

@@ -460,6 +460,7 @@ PyMODINIT_FUNC initPart()
     Part::Geometry                ::init();
     Part::GeomPoint               ::init();
     Part::GeomCurve               ::init();
+    Part::GeomBoundedCurve        ::init();
     Part::GeomBezierCurve         ::init();
     Part::GeomBSplineCurve        ::init();
     Part::GeomConic               ::init();