Move most of the net collection out of the core.

- Most units and signatures from the `net` collection
  are now in `compatibility-lib`.
- Most of the actual libraries are in the `net-lib`
  package.

original commit: 2b1fb036c63639bc5dbb65348c4f4e5802c95b53

pkgs/typed-racket-more/info.rkt

@@ -3,6 +3,7 @@
 (define collection 'multi)
 
 (define deps '("base"
+	       "net-lib"
                "draw-lib"
                "rackunit-lib"
                "typed-racket-lib"