See previous commit for discussion; it's easier to read and maintain
this rather than have the precomputed min/max comparisons.
LevelMin - minDecrease <= min && max <= LevelMax + maxIncrease;
See EncounterArea7b:
Since we know min and minDecrease (0) before doing the linq filter we
can precompute the lowbound, same for highbound; but this isn't
immediately obvious to the reader. The perf cost is pretty much
negligible in the big picture, so leave it in the more readable state.
Thanks @fattard & @ammako !
#2389
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.