add nyan-mode emacs package

pkgs/applications/editors/emacs-modes/nyan-mode/default.nix

@@ -0,0 +1,31 @@
+{trivialBuild, fetchFromGitHub}:
+
+trivialBuild rec {
+  pname    = "nyan-mode";
+  version  = "20150128";
+
+  src = fetchFromGitHub {
+    owner  = "TeMPOraL";
+    repo   = pname;
+    rev    = "41faa2c809da7b2cb3e6f8fadefae3f338ced3f2";
+    sha256 = "1idaac7sjc8hhbf5zif61ncg1pvg28c0qfihavdx61albww0ll7f";
+  };
+
+  patches = [ ./directory.patch ];
+
+  preBuild = ''
+    substituteInPlace nyan-mode.el \
+      --replace "@OUT@" "$out/"
+  '';
+
+  postInstall = ''
+    cp -r img $out
+    cp -r mus $out
+  '';
+
+  meta = {
+    description = "An analog indicator of the position in the buffer";
+    homepage = https://github.com/TeMPOraL/nyan-mode/;
+    license = "GPLv3+";
+  };
+}

pkgs/applications/editors/emacs-modes/nyan-mode/directory.patch

@@ -0,0 +1,13 @@
+diff --git a/nyan-mode.el b/nyan-mode.el
+index 939a25a..3d0b983 100644
+--- a/nyan-mode.el
++++ b/nyan-mode.el
+@@ -106,7 +106,7 @@ This can be t or nil."
+   :group 'nyan)
+ 
+ 
+-(defconst +nyan-directory+ (file-name-directory (or load-file-name buffer-file-name)))
++(defconst +nyan-directory+ "@OUT@")
+ 
+ (defconst +nyan-cat-size+ 3)
+ 

pkgs/top-level/emacs-packages.nix

@@ -593,6 +593,8 @@ let self = _self // overrides;
     meta = { licence = gpl3Plus; };
   };
 
+  nyan-mode = callPackage ../applications/editors/emacs-modes/nyan-mode {};
+
   org-plus-contrib = melpaBuild rec {
     pname   = "org-plus-contrib";
     version = "20141020";