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/net-lib/info.rkt

@@ -0,0 +1,4 @@
+#lang setup/infotab
+
+(define collection 'multi)
+(define deps '("base"))

pkgs/scribble-pkgs/scribble-lib/info.rkt

@@ -4,6 +4,7 @@
 
 (define deps '("base"
                "compatibility-lib"
+	       "net-lib"
                "at-exp-lib"
                "draw-lib" 
                "syntax-color-lib"