Adding roxterm package.

The contents of `./build.sh` look pretty good, but you should leverage the default builder where possible/feasible.

You should be able to do something along the lines of (untested):

``` nix
  # Fix up python path so the lockfile library is on it.
  PYTHONPATH = stdenv.lib.makeSearchPath "lib/{python.libPrefix}/site-packages" [
    pythonPackages.curses pythonPackages.lockfile
  ];

  buildPhase = ''
    # Fix up the LD_LIBRARY_PATH so that expat is on it
    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${expat}/lib""

    python mscript.py configure --prefix="$out"
    python mscript.py build
  '';

  installPhase = ''
    python mscript.py install

    wrapProgram "$out/bin/roxterm" \
    	--prefix XDG_DATA_DIRS : "$GSETTINGS_SCHEMAS_PATH"
  '';
```