fix license
updated source files with Metis 2.3 (timestamp: 16 Sept. 2010)
MIT license -> BSD License
copied the unmodified official Metis 2.3 (15 Sept. 2010) sources into Isabelle
change license, with Joe Hurd's permission
new version of the Metis files
remove old sources
GPL -> BSD
The Metis prover (slightly modified version from Larry);