Specification work stream

[mimoo]

I think we should find some time to focus on specifying missing parts of the system when we have some time.

We should work together to analyze what's missing, and how we can divide work : o

The current list I'm thinking about:

• poseidon
• inner product argument
• extended lookup tables (still not fully spec'ed)
• endomorphism API (there's a lot of "use the endomorphism to derive challenge from challenge' in the spec (e.g. step 20))
• group map

CC @jspada @querolita (don't worry this is just future planning :) nothing urgent)