Treat Betza-defined e.p. capture

Treat Betza-defined e.p. capture

Pieces with redefined moves that include an e.p. capture will now
not be subject to the heuristic that deletes a suspected e.p. victim
during board update (which was only applied to Pawns and Lances).
When they move to the e.p. square (still set by Pawn or Lance multi-
pushes in the old hard-coded way), this will remove the last-moved piece
(which created those e.p. rights).