Constant darkfi::validator::pow::_DIFFICULTY_CUT

const _DIFFICULTY_CUT: usize = 60;

Used to calculate how many items to retain for next difficulty calculation. We are keeping the middle items, meaning cutting both from frond and back of the ring buffer, ending up with max DIFFICULTY_WINDOW - 2DIFFICULTY_CUT items. (2DIFFICULTY_CUT <= DIFFICULTY_WINDOW-2) must be true.