When "declaring" a module using \*modindex{}, and * doesn't start with "ref",

When "declaring" a module using \*modindex{}, and * doesn't start with "ref",
set up the indexsubitem to "(in module #1)" automatically.  This reduces the
amount of markup needed in the module docs and, more importantly, makes it
o.k. to leave out in simple sections.  \setindexsubitem{} can still be used
to change or reset it.