Consider lazy assignment of terms to IDs, based on presence in payload

[dlongley]

If we are able to assign terms to IDs based on their presence in the payload, then large contexts with many (potentially unused) terms will not use up smaller ID space and any future additions to existing contexts (despite it being best practice not to change well-versioned contexts) would not change the CBOR-LD encoding of an existing payload.

This approach would probably need a new header to indicate the different way of assigning term IDs for backwards compatibility.

[dlongley]

Closing this as it would be a new processing mode. We can add such a mode in the future if we want to, we've added an area in the registry (or will add) to allow for new processing modes over time. A registry entry will say what processing mode it uses, defaulting to the "default processing mode" (which is the only mode defined right now).