Previously, we split gen 2-5 egg move validation into two phases,
`checkLearnset` where we searched for a valid father, and
`reconcileLearnset` where we made sure the father could learn the move
combination.
Egg move validation has now been completely moved out of these
functions and into `validateSource`, which calls `findEggMoveFathers`.
The new algorithm no longer requires `C` moves to be hardcoded into
`learnsets.js`, now doing a more thorough check validation for the
father's move combination. This should be slower than before, but
net performance should be massively improved due to two other
optimizations in this refactor:
- We no longer do any father-searching if the moveset can be obtained
any other way - in particular, this means no more father validation
in gen 6+ where all egg move combinations are legal anyway.
- We only check fully-evolved pokemon as fathers (because anything a
prevo can learn, its evos can learn, too - yes, we remember to make
exceptions for Salazzle, Combee, and future-gen evos)
In addition, `/learn` should now provide significantly better
information for egg move breeding, since it uses a more thorough check
instead of the validator's short-circuiting the moment it finds a valid
father.
This also improves some baby-only move validation, specifically fixing
the issue with Seismic Toss Charm Chansey.
In most other similar systems, like TeamValidator, we use `thing.dex` instead of having it extend `ModdedDex`. Battle has always extended `ModdedDex`, though. This changes Battle to match the others.
This should fix an issue with `Battle.data` not being cached.
This also frees up Battle to extend ObjectReadWriteStream<string> in a future update.
