also changed over to mschoch fork of goleveldb (temporary)
the change to my fork is pending some read-only issues described
here: https://github.com/syndtr/goleveldb/issues/111
hopefully we can find a path forward, and get that addressed upstream
refactor to share code in emulated batch
refactor to share code in emulated merge
refactor index kvstore benchmarks to share more code
refactor index kvstore benchmarks to be more repeatable