Generic cleanups

- hunt for more hardcoded variant-specific constants
  - position of captured pieces in curses mode
  - compile with bound-checker
- add autosave mode to ease hunt for segfaults ?
- use 2D array for the board, get rid of the (i)nunmap stuff
- fixup build procedure to support parallel make runs
- investigate those preexisting "overflow in implicit constant
  conversion" warnings

Minishogi-related stuff

- make minishogi a run-time option rather than a compile-time one
- minishogi patterns
- tune difficulty levels
- other tunings to investigate
  * PromotionZoneDistanceBonus
  * OPENING_HINT
- add minishogi stuff to the doc
- use valid minishogi moves in online help
