Updated the README to reflect the differences of the BigInteger
implementation (performance, and compatibility with large sets).
Extracted the BigInteger implementation and moved it into a new package.
Whoops, removed the old BigInteger implementations.
Created the LongPermutations implementation, currently as a standalone
class.
Completed the move of all implementation details to separate long and
BigInteger classes.
Removed an unnecessary instance variable for the set size.
Whoops, forgot to remove debugging output again.
Moved the instance variable for inputSetSize from the implementations as
well, at least for now.