A directory-category for terminal emulators

This is a mostly cosmetical commit, in the sense it doesn't change the contents
of any package, but reorganizes the overall Nixpkgs expressions.

Terminal emulators are an ubiquitous tool for any Unix user; even the beginners
are routinely familiarized to it. And, manifestly, there are many
implementations of terminal emulators out there, from those traditionally made
in C and C++ to those written in Haskell and Go.

Terminal emulators deserve more highlight. This commit does that by creating a
category for them.

pkgs/applications/terminal-emulators/eterm/default.nix

@@ -0,0 +1,26 @@
+{ stdenv, fetchurl
+, libX11, libXext, libXaw
+, pkgconfig, imlib2, libast }:
+
+stdenv.mkDerivation rec {
+  pname = "eterm";
+  version = "0.9.6";
+  srcName = "Eterm-${version}";
+
+  src = fetchurl {
+    url = "http://www.eterm.org/download/${srcName}.tar.gz";
+    sha256 = "0g71szjklkiczxwzbjjfm59y6v9w4hp8mg7cy99z1g7qcjm0gfbj";
+  };
+
+  nativeBuildInputs = [ pkgconfig ];
+  buildInputs = [ libX11 libXext libXaw imlib2 ];
+  propagatedBuildInputs = [ libast ];
+
+  meta = with stdenv.lib; {
+    description = "Terminal emulator";
+    homepage = "http://www.eterm.org";
+    license = licenses.bsd2;
+    maintainers = [ maintainers.AndersonTorres ];
+    platforms = platforms.linux;
+  };
+}