removed piece lists

Piece lists have been erased, and the function change is in movegen
where moves are generated in a different order.
For knights, bishops, rooks, and queens:
- the 'from' square is read from the players side
- the 'to'   square is read from the player's opposite side

The effect that I notice is that, from the starting position, fewer
nodes are searched to reach a fixed depth. (time is 30% faster to depth
14, 21, 24)
Perft runs at the same speed.
Not sure how this would do in fishtest.
The position structure is smaller as a results of deleting the movelists
and indices. Should this make multi threading faster?

I don't know if it is worth testing in fishtest - it just might be
interesting to look at the effect this has on the search performance.

The original bench takes 6.9M nodes and this version takes 8.3M nodes.
So the effect on move ordering might be actually be detrimental.