This was mostly done automatically and then visually inspected for obvious errors.
All //-style comments should have a 2-space separation from the code, and 1 space after the comment sign.
Changed the signitures of the following to use interfaces:
GetPlacementBlockTypeMeta
OnPlaced
OnPlacedByPlayer
OnDestroyed
OnNeighbourChanged
NeighbourChanged
OnUse
CanBeAt
Check