THINGS TODO
-----------
* Make "unload" be more sensible, as to what is the opposite behavior
  of "use", "unuse", "load", & "unload" in unloading a module.

* Use the "module avail" cache even for the module load/unload lookups

* Add --remove (opposite of --create) to remove cache files

* Add "exists" switch to exit with 0 or 1 if the given modulefile
  exists or not.

* Add "exec" switch to execute the given "embedded" Tcl routines
  in modulefiles.

* Add RPM distribution creation to Makefile.

* Modify how modules recurses through modulefile directories - have
  it optionally skip RCS and CVS directories.

* Add capability for modules to use a "numeric" sorting of modulefiles.