GNU Go 3.1.5 released September 15, 2001

This is a merge of 3.1.4 and 3.3.1. It implements the one-dimensional
board. It is about 10% faster than 3.1.4 and passes four more regressions.
The --enable-dfa option has also been tested.

- board changed from 2D to 1D array representation
- major revisions of board.c and reading.c
- smaller revisions more or less anywhere