set-partitions is crate that allows to represent and enumerate [partitions of a set][https://en.wikipedia.org/wiki/Partitionofa_set]
Partitions are represented as slices containing restricted growth sequences, enumerated in lexicographic order, using the algorithm from [The Art of Computer Programming Fascicle 3b, page 27, by Donald Knuth][http://www-cs-faculty.stanford.edu/~uno/fasc3b.ps.gz].