Use ii in Betza notation for 3rd-rank Pawn push

Use ii in Betza notation for 3rd-rank Pawn push

The 'i' modifier specifies the move is only for virgin pieces. We now
use 'ii' to indicate a move that can be made when the piece is standing
on the square in front of that were such a piece starts in the initial
setup. This is intended for Pawns that can still be pushed extra far
after they have made a first single step, such as in Wildebeest Chess,
where pawns on 2nd rank can move 1, 2 or 3 squares ahead, and on 3rd rank
can still move 1 or 2 (fmWifmW3iifmW2).