Remove magic number and hard type enums in DrawViewDimension.h

- Remove currently present magic numbers
- Hard type enums, so magic numbers can no longer be introduced. We don't want people to introduce magic numbers.

src/Mod/TechDraw/App/LandmarkDimension.cpp

@@ -155,7 +155,7 @@ Base::Vector3d LandmarkDimension::projectPoint(const Base::Vector3d& pt, DrawVie
     return DrawUtil::invertY(result);
 }
 
-int LandmarkDimension::getRefType() const
+DrawViewDimension::RefType LandmarkDimension::getRefType() const
 {
     //TODO: need changes here when other reference dim types added
     return DrawViewDimension::RefType::twoVertex;