- bitboard.c: make attacks for knight/king
- square macros (BB, BBfile, BBrank) renamed sq_make, sq_file,
sq_rank, moved to board.h (and become temporarily inline funcs)
- different macros/defs moved to "correct place" (bitboard/board/piece):
board.[ch]: everything related to board/square
bitboard.[ch]: everything related to bitboards
piece.[ch]: everything related to pieces
