<module>.prop rename

[jnemeth%victoria.tc.ca@localhost (John Nemeth)]

     The module subsystem has a feature where it can automatically load
a <module>.prop file along with the module.  The purpose of the file is
to store persistent args for the module and/or args for use when the
module is autoloaded.  It is also being used to store information about
the module for use by the module subsystem.

     .prop is short for proplib or property list.  It also made
coding easier as s/.kmod/.prop/ doesn't change the length of the path.
Anyways, I have received several private requests to change the name to
<module>.plist.  After thinking about it, I believe this to be a good
idea.  It seems that .plist is a somewhat standard extension for a file
that contains a property list (see Wikipedia).

     <module>.prop isn't in any release and to the best of my knowledge
there are no significant uses of it yet.  That means now is a pretty
good time to change it.  If there are no serious complaints, I'll start
working on the changes in about a week.