2.7.47 released March 13, 2000

- singleton() moved from utils.c to board.c
- new files incremental_board.c and incremental_board.h, supplying an
  implementation of incremental board updates
- support for incremental board updates added to board.c but still disabled
- updateboard() made static to board.c
- return type of pushgo() and popgo() changed to void
- new function play_move() replaces updateboard() for use from interfaces