PartDesign: refactor positionBySketch

Rename it to positionByPrevious. Rewrite.
Rewrite SketchBased::transformPlacement.

src/Mod/PartDesign/App/FeaturePad.cpp

@@ -141,7 +141,7 @@ App::DocumentObjectExecReturn *Pad::execute(void)
     SketchOrientation.multVec(SketchVector,SketchVector);
 
     try {
-        this->positionBySketch();
+        this->positionByPrevious();
         TopLoc_Location invObjLoc = this->getLocation().Inverted();
 
         base.Move(invObjLoc);