Helper functions for finding common topological elements
Added methods to get a set of cononical ids for edges and faces on cells. These can be compared to find uniqueness.
Also added a function to compute a 32-bit FNV-1a hash on Vecs of ids (which the cononical ids are). Our studies show that sorting 32-bit integers is so much faster than sorting Id3 that the extra time to resolve collisions is made up.