tablesorter update

* Upgrade tablesorter v2.16.3 -> 2.17.8

* Use default filter to put the **Episode** filter into regex mode for better matching
  > Allows you to do things like `Show Name - 5x` to see all the matching items for the season.

* Changed ignore articles from `The|A` to `The|A|An`.

* Add hack for the show 'A to Z' to not ignore the article when sorting.