[FIX] tablesorter less file: better logic for filter input background color

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52133 b456876b-0849-0410-b77d-98878d47e9d5
[MRG] Automatic merge, branches/13.x 52130 to 52133

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@52134 b456876b-0849-0410-b77d-98878d47e9d5