0.7.12.24

0.7.12.24
	Changes to PROVIDE/REQUIRE to make them (a) conform to ANSI,
	(b) any use...
	... cease nonstandardly downcasing elements in *MODULES*
	... add a list of *MODULE-PROVIDER-FUNCTIONS* which the user
   	    can hang functions off to make REQUIRE do whatever he
   	    wants it to do.
	... its default member knows how to load files in
	    $SBCL_ROOT/modulename/modulename

	First pass at a contrib infrastructure...
	... change install.sh to do new and exciting things, and as a
	    side benefit, able to install other than into /usr/local
	... amend INSTALL instructions to match

	Two contrib modules...
	... asdf here is a direct copy of the one in cclan, but
	    despite being portable and therefore not really
	    qualifying, will be v. useful for loading the others
	... bsd-sockets (db-sockets by any other name) is a fairly
	    low-level interface to the BSD socket API: high-level
	    interfaces (e.g. ACL-compatible, or CLOCC PORT) could be
	    built on top of it without getting dirty with ALIEN