The 1.0 release of the source code is available for download, and is licensed according to the GNU General Public License version 3.0 or later. If you have doxygen installed on your system, you can generate the source code documentation locally. Otherwise, it is available here.
The user guide is available under the Creative Commons Attribution-Share Alike 3.0 Unported License.
Michael Marsh, mmarsh at umiacs dot umd dot edu, 2008.