Package-level declarations

Extended info encoders are responsible for turning T into a byte buffer.

On-demand extended info encoders are invoked on every observer whenever information must be written. These differ from PrecomputedExtendedInfoEncoder in that they cannot be pre-computed, as the data in the buffer is dependent on the observer.

Pre-computed extended info encoders encode the data for all necessary extended info blocks early on in the process. This allows us to do a simple native buffer copy to transfer the data over, and avoids us having to re-calculate all the little properties that end up being encoded.