Move functions from AudacityProject to SelectActions

src/MixerBoard.cpp

@@ -828,7 +828,7 @@ void MixerBoardScrolledWindow::OnMouseEvent(wxMouseEvent& event)
       //v Even when I implement MixerBoard::OnMouseEvent and call event.Skip()
       // here, MixerBoard::OnMouseEvent never gets called.
       // So, added mProject to MixerBoardScrolledWindow and just directly do what's needed here.
-      mProject->SelectNone();
+      SelectActions::SelectNone( *mProject );
    }
    else
       event.Skip();