Follow and update according to the spec changes

Includes  (but not limited) to the following issues:
(merged) https://github.com/ethereum/consensus-specs/pull/3782
(merged) https://github.com/ethereum/consensus-specs/pull/3794
One of two will be chosen, could comment with args:
https://github.com/ethereum/consensus-specs/pull/3800
https://github.com/ethereum/consensus-specs/pull/3813
