Added Advanced Table Configuration demo to show how to persist ace:tableConfigPanel settings when using multiple header rows.

r38722:
Committed fix for issue with not restoring original row order after removing custom sorting criteria; changed beans from session-scoped to window-scoped; added configurable settings to header columns.

Regarding the issue with not restoring original row order after removing custom sorting criteria, the data model gets sorted when there's a sorting request with a custom ordering, but when all custom sort criteria are removed, the model is not sorted back to the original order, but simply left in the state it is at the moment. I tried setting a default order (sort only by id, ascending) when restoring to the default settings, but since this is done in the invoke application phase, the model doesn't get re-sorted, because the table does the sorting during decoding, initiated by a request. So what was done in the end was simply reset the model with the original data list when restoring defaults.