Eliminate many calls to RedrawProject & TrackPanel::Refresh()...

... Let the window respond to an undo manager event instead, whenever there
is a push or modify

Maybe this makes a few unnecessary redraws that did not happen before.  If
that is important, then we should figure out how to put the logic for eliding
the redraw into ProjectWindow, and the extra information needed for the
decision into the events, but not make intrusions in other code all over the
place.

src/ProjectAudioManager.cpp

@@ -146,9 +146,6 @@ You are saving directly to a slow external storage device\n\
       else
          // Add to history
          history.PushState(_("Recorded Audio"), _("Record"));
-
-      // Refresh the project window
-      window.RedrawProject();
    }
 
    // Write all cached files to disk, if any