Surface icon in the object tree

Bezier- and b-spline surfaces now have a surface icon in the tree.

src/Mod/Surface/Gui/BSurf.cpp

@@ -71,6 +71,11 @@ void ViewProviderBSurf::unsetEdit(int ModNum)
     // nothing to do
 }
 
+QIcon ViewProviderBSurf::getIcon(void) const
+{
+    return Gui::BitmapFactory().pixmap("BSplineSurf");
+}
+
 BSurf::BSurf(ViewProviderBSurf* vp, Surface::BSurf* obj)
 {
     ui = new Ui_DlgBSurf();

src/Mod/Surface/Gui/BSurf.h

@@ -45,6 +45,7 @@ namespace SurfaceGui
     public:
         virtual bool setEdit(int ModNum);
         virtual void unsetEdit(int ModNum);
+        QIcon getIcon(void) const;
     };
 
     class BSurf : public QWidget