MLS Message types

[pcapriotti]

This PR implements deserialisation for MLS message types

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[mdimjasevic]

This looks great!

Many of the data types you introduce in this PR have fields of Word* types. Would it make sense to wrap them with newtypes? If so, I would find such an alternative easier to read: once parsed, I don't care how many bytes something was in its serialised form, and on the other hand a solid type name might suggest what it is for, and it makes it harder to confuse values of the same Word* type.

[pcapriotti]

This looks great!

Many of the data types you introduce in this PR have fields of Word* types. Would it make sense to wrap them with newtypes? If so, I would find such an alternative easier to read: once parsed, I don't care how many bytes something was in its serialised form, and on the other hand a solid type name might suggest what it is for, and it makes it harder to confuse values of the same Word* type.

I think it would just add a lot of noise with not that many benefits, in this case.