Start threading Structured signature into existing datastructures.

[Carreau]

There are many objects that are called "Signature", Just a draft to try to rename the current one to "TextSignature", to differentiate, and try to pass the current one to be serialized/loaded.

[asmeurer]

I was thinking to just store the text form on the Signature object, or to have a method to reconstruct it if enough information is already there in the structured form.

As I suggested in the issue, I think it's a good idea to still include the str form in the JSON alongside the structured form.

[asmeurer]

Might be a good idea to merge this and #289 together to avoid conflicts.

[Carreau]

I was thinking to just store the text form on the Signature object, or to have a method to reconstruct it if enough information is already there in the structured form.

As I suggested in the issue, I think it's a good idea to still include the str form in the JSON alongside the structured form.

Yes, I was just experimenting on seeing how far I could get for simpler signature, and ended up going further than I thoughts

Might be a good idea to merge this and #289 together to avoid conflicts.

It's on my todo. I was not planning to go that far and tried to stay away from this file, but ended up touch it anyway. I'll try to find some time to merge the two, or split this one in smaller chunks.