Cardano Updates

Validation checks that:

* current protocol version is within the era's bounds
* previous protocol version is at most the current version
* previous protocol version + 1 is within the era's protocol version bounds

Validation checks that:

* current protocol version is within the era's bounds
* previous protocol version is at most the current version
* previous protocol version + 1 is within the era's protocol version bounds

Without a certify blocks or a certify transactions form, it will be
added later.

* mithril-aggregator from `0.8.42` to `0.8.43`
* mithril-common from `0.6.63` to `0.6.64`
* mithril-signer from `0.3.29` to `0.3.30`

This offset was applied at the end of the computation irrespective of
the security parameter.
It's applied to factor for the fact that block ranges ends are
exclusive, allowing the computed number to be strictly a block range end
(e.g. 14, 29, 49, ... instead of 15, 30, 50, ... which are ranges start
numbers).

The new blocks transactions signature can now handle partial range, so
this offset can be removed.