RAND: use unsigned long instead of mp_digit
RAND: use unsigned long instead of mp_digit

if we use mp_set_int() instead of mp_set(), then we can use
full unsigned long integers instead of single digits. This
seems a lot safer, especially for future versions of the
random algorithm.

RAND: merged a conflict

hasufell/pqc,hasufell/pqc,hasufell/pqc