Table Data source now created by NIB

This allows sending actions directly to the table data source (which will thus act as the main controller for that list). This is necessary for proper context menu support.
Added undo support for story list.

Now additions to and removals from the story list can be undone and redone.
Implemented context menu for table view
Validate menu items

This will make the "Send again" menu item greyed out if nothing is selected.