start bitboard init (see commit details)

- 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

src/chessdefs.h

@@ -16,20 +16,10 @@
 
 #include "brlib.h"                                /* brlib types */
 
-#define mask(i)        ( 1ULL << (i) )
 #define C64(const_u64) const_u64##ULL
 #define U64(const_s64) const_s64##LL
 
-typedef u64 bitboard;
-typedef ushort board;
-
-
-/* flip a 0-63 square:
- * Vertical:   G8 (62) becomes G1 (6)
- * Horizontal: G8 (62) becomes B8 (57)
- */
-#define FLIP_V(sq)      ((sq) ^ 56)
-#define FLIP_H(sq)      ((sq) ^ 7)
+//typedef ushort board;
 
 #define BOARDSIZE    (8*8)
 /* from human to machine */