[RCLib] Allow indexing by biome

[SleepSoul]

GetFromList checks biome but it's just a constant that's always "Tartarus". Easy enough to check, just look at NextRoomSet and PrevRoomSet and figure it out.

[SleepSoul]

Pushing to 1.3 as 1.2 featureset needs trimming.

[alexmaichen]

Is this as simple as RCLib.CurrentBiome = currentRoom.RoomSetName or "Tartarus" in DoUnlockRoomExits and StartRoom wrappers, and probably reinitializing it to "Tartarus" at the start of the run (in the StartNewRun wrapper) too? I have a prototype like this (dev branch on my fork of the repo) that seems to work.