Added 4-3
Added 4-4

The sections thing isn't implemented yet, but the skeleton *should* be
good.
Added 5-1
Added Cannon, BulletBill things

jumpFrequency and fireFrequency have just been renamed to frequency now.
Added 5-2

Transport/entrance attributes haven't been set, but that'll come once
Vines are implemented.
Added 5-3
Added 5-4
Added 6-1
Added Lakitu, SpinyEgg, Spiny things