Identify wcf91 as wCurPartySpecies, wCurItem, and wCurListMenuItem

[Rangi42]

wcf91 corresponds to these bytes in pokegold:

wCurItem:: db
wCurItemQuantity::
wMartItemID::
	db

wCurPartySpecies:: db

(Note the labels after it, e.g. pokered wWhichPokemon corresponds to pokegold wCurPartyMon, wHPBarType to wWhichHPBar, wRemoveMonFromBox to wPokemonWithdrawDepositParameter, etc.)

Unlike in pokegold, the species ID and item ID share a byte. This is important for DisplayListMenuID and probably elsewhere.

[Rangi42]

The ideal way to test that this PR is accurate would be to split the labels into separate bytes, manually add copying in any places which rely on them to be identical (AFAIK only in DisplayListMenuID, which has asserts to that effect), and then play the game. But that's a lot of trouble. :P

Edit: Playing up to Vermilion City, doing stuff like checking the Pokedex, teaching TMs, evolving Pokemon, trade evolutions, etc, behaves just fine when I split them up. So @dannye I'm confident this label splitting is accurate. :)