In future implementations of Context 0.x, we need a way to assign non-optimal keys if optimal keys are beyond 20 bits

[Yoric]

Context 0.1 specifies that we can only use 20 bits for a key. We're currently using an algorithm that always returns optimal-for-space keys and this algorithm may fail by exhausting the 20 bits while less optimal-for-space algorithms could succeed.

We should devise a backup strategy that will work in cases in which we currently fail.