Path: added Path.fromShapes and Path.sortWires

* Path.fromShapes can now convert any number of shapes to Path with
optimzied travel distances. It internally uses Path.sortWires to
minimize travel distances, and also sort wires by its Z height in case
of sectioned wires.

* The above python function is impelmented in Path::Area class.

* Path::FeatureShape is rewrote to take advantage of these two
functions.

* Add Path::FeatureAreaView to partially display a Path::FeatureArea's
sections.

src/Mod/Path/Gui/AppPathGui.cpp

@@ -80,6 +80,8 @@ PyMODINIT_FUNC initPathGui()
     PathGui::ViewProviderPathPython         ::init();
     PathGui::ViewProviderArea               ::init();
     PathGui::ViewProviderAreaPython         ::init();
+    PathGui::ViewProviderAreaView           ::init();
+    PathGui::ViewProviderAreaViewPython     ::init();
 
      // add resources and reloads the translators
     loadPathResource();