latest update, undo manager working better, need to implement redo for a few...

latest update, undo manager working better, need to implement redo for a few senarios, and fix undo when deleting the last remaining cell in a grid

git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/trunk/TableTool@6207 57e6efec-57d4-0310-aeb1-a6c144bb1a8b