Factor some logic out of SketchMap using logic from SketchMap1 instead.

This is an API compatible change.

Shortcomings:
  * I was unable to factor functionality out of SketchMapParams due to
    only having the hashes and not the hash seed.
  * I was also unable to factor ++ and + because I don't have access to
    the implicit serialization, which I need to create a SketchMapMonoid