hoist fennel and lua dbus-proxy into overlay.nix

updated the shell.nix files in both the programs that use them, so
hopefully this is not too invidious for isolated development

saturn/dbus-proxy.nix

@@ -1,29 +0,0 @@
-{ lua, lgi, buildLuaPackage, fetchFromGitHub }:
-let
-
-  simpleName = "dbus_proxy";
-
-in
-# TODO: add busted and checkPhase?
-buildLuaPackage rec {
-  version = "0.10.2";
-  pname = simpleName; # nixpkgs unstable needs this
-  name = "${pname}-${version}"; # nixpkgs 21.11 needs this
-
-  src = fetchFromGitHub {
-    owner = "stefano-m";
-    repo = "lua-${simpleName}";
-    rev = "v${version}";
-    sha256 = "0kl8ff1g1kpmslzzf53cbzfl1bmb5cb91w431hbz0z0vdrramh6l";
-  };
-
-  propagatedBuildInputs = [ lgi ];
-
-  buildPhase = ":";
-
-  installPhase = ''
-    mkdir -p "$out/share/lua/${lua.luaversion}"
-    cp -r src/${pname} "$out/share/lua/${lua.luaversion}/"
-  '';
-
-}

saturn/default.nix

@@ -1,5 +1,6 @@
 { stdenv
 , callPackage
+, fennel
 , fetchFromGitHub
 , fetchurl
 , gobject-introspection
@@ -7,20 +8,12 @@
 , lib
 , librsvg
 , lua53Packages
+, luaDbusProxy
 , lua5_3
 , makeWrapper
 , writeText
 }:
-let fennel = fetchurl {
+let inifile = let lua = lua5_3; in lua53Packages.buildLuaPackage rec {
-      name = "fennel.lua";
-      url = "https://fennel-lang.org/downloads/fennel-1.0.0";
-      hash = "sha256:1nha32yilzagfwrs44hc763jgwxd700kaik1is7x7lsjjvkgapw7";
-    };
-    dbusProxy = callPackage ./dbus-proxy.nix {
-      inherit (lua53Packages) lgi buildLuaPackage;
-      lua = lua5_3;
-    };
-    inifile = let lua = lua5_3; in lua53Packages.buildLuaPackage rec {
       pname  = "inifile";
       name = "${pname}-${version}";
       version  = "1.0.2";
@@ -38,7 +31,7 @@ let fennel = fetchurl {
     };
 
     lua = lua5_3.withPackages (ps: with ps; [
-      dbusProxy
+      luaDbusProxy
       inifile
       inspect
       lgi

saturn/shell.nix

@@ -1,4 +1,4 @@
-with import <nixpkgs> {} ;
+with import <nixpkgs> { overlays = [ (import ../../overlay.nix) ];  } ;
 (callPackage ./. {
 }).overrideAttrs(o: {
   GDK_PIXBUF_MODULE_FILE = "${pkgs.librsvg.out}/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache";