Switch back to pmap for top-level folding of operations into worlds.
jvm opts: drop compressed OOPS
Add cliff click's high scale lib
Revert "Switch back to pmap for top-level folding of operations into worlds."

This reverts commit 13688d525d21cd5a9f8ed9ac9d626e2285ef47fd.
linearizable-prefix: optimize degenerate histories

Linearizable-prefix doesn't care about which history it reports, so long
as it gets there. We use degenerate-worlds to prune worlds with
equivalent models and pending operations from the search space.
*drastically* cuts branching ratio: a 50-element CAS Register history
went from 200,000 worlds to low double digits, and 230,000 ms to 135ms.