Continue rewrite for issue #19

* Add utility bookkeeping so that utilities are not re-acquired if they
  have already been downloaded.

* Remove network dependency DRAKMA, as well as old http/web-apis

* Make loading of QUICKUTIL-UTILITIES quiet except for some verbose
  status output. (This should be configurable in the future.)

* Remove proof-of-concept UTILS function.

* Rewrite WHO-PROVIDES to use new framework.

* Rewrite UTILIZE to use new framework.

* Add UTILITIES-FOR for computing symbol/category utilities.

* Remove dead code in defutil.lisp.

Sorry for the huge commit with lots of different functionality additions
and removals!