add repetition detection, root position count

- hist.c: add hist_next() - get next entry in history
- state_t: remove plycount, clock_50 -> ply50, add phase, repcount
- pos_t: add plycount, plyroot
- state_t moved to chessdefs.h
- perft-test: split perft from do_perft (todo for perft_alt)
- position.c: add pos_repcount()
- search.c: add is_draw()
- uci: set root position (after moves), adjust history moves repcount

src/eval-defs.h

@@ -14,7 +14,6 @@
 #ifndef EVAL_DEFS_H
 #define EVAL_DEFS_H
 
-
 #include "chessdefs.h"
 #include "piece.h"
 #include "eval.h"
@@ -26,7 +25,6 @@ enum {
     ENDGAME,
     PHASE_NB
 };
-typedef s16 phase_t;
 
 /* pieces weight in phase calculation.
  */