DexLevel was the initial abstraction, which was expanded/reused for
evolution details
I should probably merge the two classes since everything is passed as
EvoCriteria
The encounter generators do some silly form fuzzy match which can now be
more accurately checked since I've moved Form to DexLevel... maybe a
future commit can clean that up.
encounterarea2 was reusing this class, just use a throwaway readonly
struct as our temp value storage
Now logic is reasonably split, and each format of area has its own way
of yielding slots
Too much junk with checking flute boosts or catch combo applicability;
just let the area dictate how slots match.
