Factor as much logic as possible into SketchmapMonoid1

This commit factors the implementation into the Monoid. This allows only
the Monoid to be concerned with the sketchmap parameters. This also
follows the create-in-the-Monoid pattern as in HyperLogLog.
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
Merge pull request #251 from cheecheeo/sketchmap_ala_hll

Factor as much logic as possible into SketchmapMonoid1