orion: add GTK3 theme

pkgs/misc/themes/orion/default.nix

@@ -0,0 +1,24 @@
+{ stdenv, fetchgit, gtk-engine-murrine }:
+
+stdenv.mkDerivation {
+  name = "orion-1.5";
+
+  src = fetchgit {
+    url = "https://github.com/shimmerproject/Orion.git";
+    rev = "refs/tags/v1.5";
+    sha256 = "995671990514a68192dc82ed51eaa6ab17c396950e1d8b7768c262027be6b05f";
+  };
+
+  propagatedUserEnvPkgs = [ gtk-engine-murrine ];
+
+  phases = "$prePhases unpackPhase installPhase fixupPhase $postPhases";
+  installPhase = ''
+    mkdir -p $out/share/themes/orion
+    cp -r gtk-2.0 gtk-3.0 metacity-1 openbox-3 xfwm4 $out/share/themes/orion
+  '';
+
+  meta = {
+    homepage = https://github.com/shimmerproject/Orion;
+    license = stdenv.lib.licenses.gpl3Plus;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -12414,6 +12414,8 @@ let
     geoclue = geoclue2;
   };
 
+  orion = callPackage ../misc/themes/orion {};
+
   oxygen-gtk2 = callPackage ../misc/themes/gtk2/oxygen-gtk { };
 
   oxygen-gtk3 = callPackage ../misc/themes/gtk3/oxygen-gtk3 { };