Include Monaco for Powerline

This probably shouldn't be included within a git repo, but it's small enough that we're not going to fret about it too much.

pkgs/monaco-powerline/default.nix

@@ -0,0 +1,22 @@
+{ lib, stdenvNoCC }:
+
+stdenvNoCC.mkDerivation rec {
+  pname = "monaco-powerline";
+  version = "1.0";
+
+  # This font is located in the same directory.
+  dontUnpack = true;
+
+  installPhase = ''
+    runHook preInstall
+
+    install -Dm644 ${./monaco-for-powerline.otf} -t $out/share/fonts/opentype
+
+    runHook postInstall
+  '';
+
+  meta = with lib; {
+    description = "The Monaco font, but patched to include powerline symbols";
+    platforms = platforms.all;
+  };
+}