BSplineCurve approximate, fix function sometime failing with smoothing algo

src/Mod/Part/App/BSplineCurvePy.xml

@@ -300,7 +300,7 @@ from the knots table of this B-Spline curve.</UserDocu>
 					Replaces this B-Spline curve by approximating a set of points.
 					The function accepts keywords as arguments.
 
-					approximate2(Points = list_of_points) 
+					approximate(Points = list_of_points) 
 
 					Optional arguments :
 

src/Mod/Part/App/BSplineCurvePyImp.cpp

@@ -840,7 +840,15 @@ 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 (!(c == GeomAbs_C0 || c == GeomAbs_C1 || c == GeomAbs_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);