Use same JQuery tablesorter library everywhere.

One-sentence description

Use same JQuery tablesorter library everywhere.

Why?

It would be better to use the same library everywhere.

Current implementation

• The event backend uses christianbach/tablesorter.
• The pizza frontend uses kylefox/jquery-tablesort.

Suggested implementation

Use Mottie/tablesorter. Mottie/tablesorter is a fork of christianbach/tablesorter with some nice added features (for example no more eval() usage).