- introduced XGridColumn.Flexibility, determining to which degree the column is resized during auto-column-resizing
- removed XGridColumn.PreferredWidth - there really is no need for this anymore now
- documented the relationship between XGridColumn.Flexibility and XGridColumn.Resizeable
- re-implemented TableControl_Impl::impl_ni_updateColumnWidths, with (hopefully) less magic
the XGridColumn (UnoControlTableColumn, implementing IColumnModel) should do this, and then multiplex
the changes to the TableControl(_Impl) instance. This way, other IColumnModel implementations also
properly trigger control updates, provided they simply properly notify their changes.