Adding Hopscotch Hashing

[barufa]

Hi!
I has been thinking about implementing a Hopscotch hashing to extend the library.
Hopscotch is said to provide good performance at very high table load factors, even ones exceeding 0.9.
However, I am not sure about how fast it could be on haskell due to bit manipulation.
Have you ever try to implement it? @gregorycollins

[gregorycollins]

No but as I understand it's similar to cuckoo? I'm happy to take a patch