in approximate, don't autocorrect continuity. Explain requirements in UserDocu instead

src/Mod/Part/App/BSplineCurvePy.xml

@@ -315,7 +315,7 @@ from the knots table of this B-Spline curve.</UserDocu>
 					points using variational smoothing algorithm, which tries to minimize 
 					additional criterium: 
 					LengthWeight*CurveLength + CurvatureWeight*Curvature + TorsionWeight*Torsion
-					Continuity must be C0, C1 or C2, else defaults to C2.
+                                        Continuity must be C0, C1(with DegMax >= 3) or C2(with DegMax >= 5).
 
 					Parameters = list of floats : knot sequence of the approximated points.
 					This argument is only used if the weights above are all null.

src/Mod/Part/App/BSplineCurvePyImp.cpp

@@ -840,17 +840,6 @@ PyObject* BSplineCurvePy::approximate(PyObject *args, PyObject *kwds)
         
         if (weight1 || weight2 || weight3) {
             // It seems that this function only works with Continuity = C0, C1 or C2
-            if (degMax < 3) {
-                c = GeomAbs_C0;
-            }
-            else if (degMax < 5) {
-                if (!(c == GeomAbs_C0)) {
-                    c = GeomAbs_C1;
-                }
-            }
-            else if (!(c == GeomAbs_C0 || c == GeomAbs_C1 || c == GeomAbs_C2)) {
-                c = GeomAbs_C2;
-            }
             GeomAPI_PointsToBSpline fit(pnts, weight1, weight2, weight3, degMax, c, tol3d);
             Handle_Geom_BSplineCurve spline = fit.Curve();
             if (!spline.IsNull()) {

src/Mod/Part/App/BSplineSurfacePy.xml

@@ -695,6 +695,7 @@
 					- X0, dX, Y0, dY (floats) with Points = 2Darray of floats
 					- ParamType = 'Uniform','Centripetal' or 'ChordLength'
 					- LengthWeight, CurvatureWeight, TorsionWeight (floats)
+					(with this smoothing algorithm, continuity C1 requires DegMax >= 3 and C2, DegMax >=5)
 					
 					Possible combinations :
 					- approximate(Points, DegMin, DegMax, Continuity, Tolerance)

src/Mod/Part/App/BSplineSurfacePyImp.cpp

@@ -1329,13 +1329,6 @@ PyObject* BSplineSurfacePy::approximate(PyObject *args, PyObject *kwds)
         }
         else if (!(weight1 == 0) || !(weight2 == 0) || !(weight3 == 0)) {
             // one of the weights is not null, we use the smoothing algorithm
-            // adjust continuity for low values of degMax, instead of failing
-            if (degMax < 3) {
-                c = GeomAbs_C0;
-            }
-            else if ((degMax < 5) && (c == GeomAbs_C2)) {
-                c = GeomAbs_C1;
-            }
             surInterpolation.Init(interpolationPoints, weight1, weight2, weight3, degMax, c, tol3d);
         }
         else {