graywolf is a fork of TimberWolf 6.3.5

TimberWolf was developed at Yale University, and was distributed as open source
for a time until it was taken commercial. The last open-source version of
TimberWolf does not perform detail routing, but is a professional-grade
placement tool. In order to continue improving the open-source version, graywolf
has been forked off from version 6.3.5 of TimberWolf.

The main improvement in graywolf is that the build process is more streamlined
and that it behaves as a normal linux tool - you can call it from anywhere and
no environment variables must be set first.