Changelog for sessions-2008.2.28

The most recent changes are at the top of this file. 2008 02 28 Interleaving appears. Type sigs get bigger. The night gets darker. But it all works. One example so far using interleaving. Need to deal properly with public channels and need to write multi-recv. 2008 02 23 Added better examples to the Tests.hs module, including the standard and much loved "calculator". Altered 'run' and '~||~' so that they automatically add the necessary 'sjump's. Corrected some documentation mistakes. Also corrected the fixity of ~>> and ~>>=. 2008 02 20 Completed rewrite. New version released to Hackage. Works correctly in GHC 6.8.2. Now permits arbitrarily complex session types with mixed branching and looping.