Refactor Idris packaging infrastructure

The main two changes are

1. Completely rewrite how with-packages works to remove use of envHooks
2. The package description is now an idris specific set rather than
    being a subset of the arguments to mkDerivation. This mirrors the
    way Haskell packages are treated.

pkgs/development/idris-modules/lightyear.nix

@@ -10,8 +10,11 @@
 let
   date = "2017-09-10";
 in
-build-idris-package {
-  name = "lightyear-${date}";
+build-idris-package  {
+  name = "lightyear";
+  version = date;
+
+  idrisDeps = [ prelude base effects ];
 
   src = fetchFromGitHub {
     owner = "ziman";
@@ -20,8 +23,6 @@ build-idris-package {
     sha256 = "05x66abhpbdm6yr0afbwfk6w04ysdk78gylj5alhgwhy4jqakv29";
   };
 
-  propagatedBuildInputs = [ prelude base effects ];
-
   meta = {
     description = "Parser combinators for Idris";
     homepage = https://github.com/ziman/lightyear;