Performance: don't colorize grid on selection

There's no possibility that the content changes based on selection
only, so doing while grid re-colorization is waste

Author: yanne

src/robotide/editor/kweditor.py

@@ -149,7 +149,6 @@ def OnSettingsChanged(self, data):
     def OnSelectCell(self, event):
         self._cell_selected = True
         GridEditor.OnSelectCell(self, event)
-        self._colorize_grid()
         event.Skip()
 
     def OnKillFocus(self, event):