PartDesign: New features AdditiveHelix and SubtractiveHelix

These features, based on the code for the Pipe class, allow the user
to simply create a helical sweep within PartDesign workbench.

Sample application is threads, springs, coils, augers, etc.

Also, remove needless requirement for positive cone angle on helixes.

Thanks to @bitacovir for helping with the icons
Thanks to @chennes for review
Thanks to @vosk for review
Thanks to @wwmayer for review

Enforce that links stay within scope for ProfileBased features
This also ensures that the Body itself is not used for creating features within
the body, causing a "Graph not a DAG" error.

src/Mod/PartDesign/Gui/AppPartDesignGui.cpp

@@ -61,6 +61,7 @@
 #include "ViewProviderThickness.h"
 #include "ViewProviderPipe.h"
 #include "ViewProviderLoft.h"
+#include "ViewProviderHelix.h"
 #include "ViewProviderShapeBinder.h"
 #include "ViewProviderBase.h"
 
@@ -156,6 +157,7 @@ PyMOD_INIT_FUNC(PartDesignGui)
     PartDesignGui::ViewProviderPrimitive     ::init();
     PartDesignGui::ViewProviderPipe          ::init();
     PartDesignGui::ViewProviderLoft          ::init();
+    PartDesignGui::ViewProviderHelix         ::init();
     PartDesignGui::ViewProviderBase          ::init();
 
      // add resources and reloads the translators