Extracted the essence of the hop-scotch algorithm into its own class

as well as extracted all colleague interfaces/classes into its own
hopscotch package.

Extracted the table aspect out into a Table interface.

Also added API-wise support for values, so that maps can be implemented.

PrimitiveLongHopScotchHashSet methods are one-liners delegating to the
hop-scotch algorithm, passing in all necessary little objects that the set
provides and maintains itself.