Path.Area: change fromShape() 'start' parameter behavior

'start' used to mean the initial resting position of the tool. Now it
is changed to mean the feed start position.

fromShape() has also improved to automatically guess 'retraction' and
'resume_height' parameters if not given, based on input shape boundary.

src/Mod/Path/App/FeaturePathShape.cpp

@@ -55,7 +55,7 @@ PARAM_ENUM_STRING_DECLARE(static const char *Enums,AREA_PARAMS_PATH)
 FeatureShape::FeatureShape()
 {
     ADD_PROPERTY(Sources,(0));
-    ADD_PROPERTY_TYPE(StartPoint,(Base::Vector3d()),"Path",App::Prop_None,"Path start position");
+    ADD_PROPERTY_TYPE(StartPoint,(Base::Vector3d()),"Path",App::Prop_None,"Feed start position");
     PARAM_PROP_ADD("Path",AREA_PARAMS_PATH);
     PARAM_PROP_SET_ENUM(Enums,AREA_PARAMS_PATH);
 }