mate: organize packages in base and extra

pkgs/desktops/mate/default.nix

@@ -1,5 +1,7 @@
 { callPackage, pkgs }:
+
 rec {
+
   atril = callPackage ./atril { };
   caja = callPackage ./caja { };
   caja-extensions = callPackage ./caja-extensions { };
@@ -8,11 +10,30 @@ rec {
   };
   engrampa = callPackage ./engrampa { };
   eom = callPackage ./eom { };
-  pluma = callPackage ./pluma { };
   mate-common = callPackage ./mate-common { };
   mate-desktop = callPackage ./mate-desktop { };
   mate-icon-theme = callPackage ./mate-icon-theme { };
   mate-icon-theme-faenza = callPackage ./mate-icon-theme-faenza { };
   mate-terminal = callPackage ./mate-terminal { };
   mate-themes = callPackage ./mate-themes { };
+  pluma = callPackage ./pluma { };
+
+  basePackages = [
+    caja
+    mate-common
+    mate-desktop
+    mate-icon-theme
+    mate-themes
+  ];
+
+  extraPackages = [
+    atril
+    cajaWithExtensions
+    engrampa
+    eom
+    mate-icon-theme-faenza
+    mate-terminal
+    pluma
+  ];
+  
 }