B-spline surface operation enabled

I have converted Nate's b-spline generation to use my superclass
FeatureBSurf and added it to the GUI. Other half-ready operations as
filling and cut are commented out.

Missing:
- the fill type must be queried from the user. The data panel lets it
modify, but it is not user-friendly.
- b-spline surface is generated, but it covers only a fraction of the
supporting curves. It may lie on OCC error.

src/Mod/Surface/Gui/Workbench.cpp

@@ -54,8 +54,9 @@ Gui::MenuItem* Workbench::setupMenuBar() const
     root->insertItem( item, surface );
     surface->setCommand("Surface");
     *surface << "Surface_Bezier";
-    *surface << "Surface_Filling";
-    *surface << "Surface_Cut";
+    *surface << "Surface_BSpline";
+/*    *surface << "Surface_Filling";
+    *surface << "Surface_Cut";*/
 
     return root;
 }
@@ -67,8 +68,9 @@ Gui::ToolBarItem* Workbench::setupToolBars() const
     Gui::ToolBarItem* surface = new Gui::ToolBarItem(root);
     surface->setCommand( "Surface" );
     *surface << "Surface_Bezier";
-    *surface << "Surface_Filling"; 
-    *surface << "Surface_Cut"; 
+    *surface << "Surface_BSpline";
+/*    *surface << "Surface_Filling";
+    *surface << "Surface_Cut"; */
 
     return root;
 }