Base: Implement TimeElapsed

Some instances of TimeInfo serve the sole purpose of measuring time
duration. Using system time is unfortunate as it returns wall clock,
which is not guaranteed to be monotonic. Replace such a usage with
the new TimeElapsed class based on steady clock.

src/Mod/Part/Gui/ViewProviderExt.cpp

@@ -921,7 +921,7 @@ void ViewProviderPartExt::updateVisual()
     }
 
     // time measurement and book keeping
-    Base::TimeInfo start_time;
+    Base::TimeElapsed start_time;
     int numTriangles=0,numNodes=0,numNorms=0,numFaces=0,numEdges=0,numLines=0;
     std::set<int> faceEdges;
 
@@ -1281,7 +1281,7 @@ void ViewProviderPartExt::updateVisual()
 
 #   ifdef FC_DEBUG
         // printing some information
-        Base::Console().Log("ViewProvider update time: %f s\n",Base::TimeInfo::diffTimeF(start_time,Base::TimeInfo()));
+        Base::Console().Log("ViewProvider update time: %f s\n",Base::TimeElapsed::diffTimeF(start_time,Base::TimeElapsed()));
         Base::Console().Log("Shape tria info: Faces:%d Edges:%d Nodes:%d Triangles:%d IdxVec:%d\n",numFaces,numEdges,numNodes,numTriangles,numLines);
 #   else
     (void)numEdges;