Make WebKit use libsoup 2.31.2 via deepOverride. Edit a few packages that were overridable but did not allow extra arguments. Remove a catch with deepOverride that pkgs.lib had this attribute in a different sense.

svn path=/nixpkgs/trunk/; revision=22529

pkgs/development/libraries/zlib/default.nix

@@ -1,4 +1,4 @@
-{stdenv, fetchurl, static ? false}:
+{stdenv, fetchurl, static ? false, ...}:
 
 stdenv.mkDerivation {
   name = "zlib-1.2.3";