Merge the fem_sprite columns into has_gender_differences. #363

Chimecho does not have gender differences; its Platinum and HG/SS second-
frame female backsprites have one hand posed a little differently, but
no actual design differences.

Torchic does count even though the only difference is a single-pixel dark
speck on the male's rear; the speck was carried over into B/W even though
the backsprites were entirely redone, so I'm guessing it either was
deliberate or has ascended into canon via "let's throw it in anyway."