Gen3 RNG

[theastrogoth]

Basic implementations of some RNG stuff:

• calculate the RNG state from an initial seed and number of RNG advances
• RNG state -> PID
• RNG state -> IVs
• PID -> nature, gender, ability, shininess
• search across a range of seeds / advances

This should be sufficient for automating static/gift RNG in FRLG, but it is missing a few things relevant to random encounters (which require information about encounter slots for generating species/levels).

This also will enable an SID-setting program to read a TID from the trainer card and report what SIDs were most likely hit.