A function to calculate lipmaa sequence numbers.
From the bamboo spec: "The lipmaalinks are chosen such that for any pair of entries there is a path from the newer to the older one of a length logarithmic in their distance."
use lipmaa_link::lipmaa; let result = lipmaa(13); assert_eq!(result, 4);
Calculates the lipmaa link number given the current sequence number.