[FIX] tablesorter: better array merging between default, table and user settings

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@46584 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] tablesorter: better element identifier for placeholder text

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@46585 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] tablesorter: missed some settings that should not be set if ajax is not being used

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@46586 b456876b-0849-0410-b77d-98878d47e9d5