Lise

* Overhaul the entire caching infrastructure, which should greatly cut down on
crashes. No new features, but it does make some changes to the database
schema.

* Fix pawn duplication in ELiDE

* Fix a different way pawns could disappear in ELiDE

* Fix disappearing pawns in ELiDE

* Fix worker process states getting desynchronized when you made a new character
* Fix methods not being callable in worker processes
* Improved performance when planning a lot of future state
* Made the LiSE engine itself an Executor, which I guess breaks compatibility.
Whatever, zerover makes no promises. Use `Engine.submit(..)` to schedule
computation in worker processes now.
* Made ELiDE's stat list scrollable

* Fix ELiDE crash when adding graph-shaped world state to a grid-shaped world