[FIX] tablesorter: keep dimming from being triggered when checkboxes are clicked. Not needed in later versions due to fixes in tablesorter (thanks Jonny!)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@52655 b456876b-0849-0410-b77d-98878d47e9d5