range of integers given as ri or as a two-element integer
y
an integer vector of elements to exclude
revx
FALSE as is, TRUE to reverse the direction and sign of rx
revy
FALSE as is, TRUE to reverse the direction and sign of y
Details
determines the range of the integers y and checks if the density justifies use
of a bit vector; if yes, uses a bit vector for the set operation; if no,
falls back to a quicksort and merge_rangediff