Fix \withsubitem so that it actually works if the only indexing macro in

Fix \withsubitem so that it actually works if the only indexing macro in
the content body is the \ttindex macro, which seems to match actual usage.

Adjust \funcline to restore the "index sub-item" for functions to be
" (in module <name>)" instead of " (in <name>)".  This is need to match
uses of \withsubitem throughout the documentation.  (Not ideal, but
gets achieves consistency.)