Surface: several improvements

* fix crash because of incomplete inheritance of BlendPoint and BlendCurve -> do not inherit from BaseClass
  as consequebce make destructor non-virtual and remove getPyObject
* pass std::vector by const reference
* remove unneeded includes
* use more suitable Python exception types
* when returning with null from Python handler then set an exception
* harmonize file guards
* several optimizations or simplifications
* use modern C++
* harmonize command name
* fix copyright note

src/Mod/Surface/Gui/Workbench.cpp

@@ -57,7 +57,7 @@ Gui::MenuItem *Workbench::setupMenuBar() const
              << "Surface_Sections"
              << "Surface_ExtendFace"
              << "Surface_CurveOnMesh"
-             << "BlendCurve";
+             << "Surface_BlendCurve";
     /*
     *surface << "Surface_Cut";
     */
@@ -76,7 +76,7 @@ Gui::ToolBarItem *Workbench::setupToolBars() const
              << "Surface_Sections"
              << "Surface_ExtendFace"
              << "Surface_CurveOnMesh"
-             << "BlendCurve";
+             << "Surface_BlendCurve";
     /*
     *surface << "Surface_Cut";
     */