* Turns DNA sequences (for context covariates) into bit sets for maximum compression
* Allows variable context size representation guaranteeing uniqueness.
* Works with long precision, so it is limited to a context size of 31 bases (can be extended with BigNumber precision if necessary).
* Unit Tests added
* Knuth-shuffle is a simple, yet effective array permutator (hope this is good english).
* added a simple randomSubset that returns a random subset without repeats of any given array with the same probability for every permutation.
* added unit tests to both functions
Mauricio Carneiro
David Roazen