[TD]getters and setters for geometry

- make attributes private (or protected) and use
  getters and setters instead of accessing attributes
  directly.

src/Mod/TechDraw/App/DimensionReferences.cpp

@@ -42,10 +42,10 @@ TopoDS_Shape ReferenceEntry::getGeometry() const
         std::string gType = geomType();
         if (gType == "Vertex") {
             auto vgeom = dvp->getVertex(getSubName());
-            return vgeom->occVertex;
+            return vgeom->getOCCVertex();
         } else if (gType == "Edge") {
             auto egeom = dvp->getEdge(getSubName());
-            return egeom->occEdge;
+            return egeom->getOCCEdge();
         } else if (gType == "Face") {
             auto fgeom = dvp->getFace(getSubName());
             return fgeom->toOccFace();