This is a surprisingly minor refactor considering how many files it
touches, but most of this is only renames.
In terms of file renames:
- `tools.js` is now `sim/dex.js`
- `battle-engine.js` is now `sim/index.js` and its three classes are
in `sim/battle.js`, `sim/side.js`, and `sim/pokemon.js`
- `prng.js` is now `sim/prng.js`
In terms of variable renames:
- `Tools` is now `Dex`
- `BattleEngine` is now `Sim`
- `BattleEngine.Battle` is now `Sim.Battle`
- `BattleEngine.BattleSide` is now `Sim.Side`
- `BattleEngine.BattlePokemon` is now `Sim.Pokemon`
Sometimes mods would mess up if they were loaded in the wrong order.
Specifically, some autogenerated properties of e.g. moves need to be
recalculated for mods.
Anyway, the entire cache system is replaced with a newer, faster,
slightly-more-memory-intensive-but-only-slightly cache system, which
no longer has these kinds of loading order issues.