Asset reissuance

[altafan]

This must be taken into account for adding support for creating reissuance transaction:

ElementsProject/elements#259

It will be mandatory to check that the input used for reissuing the asset (actually must be a token prev output) is confidential.

[altafan]

Given the Elements issue above, and stated that similar to AddIssuance, this should be a function of the updater type, it will be necessary that the chosen partial input has a (Non)WitnessUtxo so that we can check that it's actually a confidential input, otherwise we should return an error.

This error should suggest the user move his reissuance token to a confidential address otherwise he will never be able to reissue his asset.

[altafan]

It is mandatory that the input that contains the reissuance of the asset is the token output generated when this was issued.
Also, the token output must be added to the outputs of the reissuance transaction with exactly the same amount of the input.

Given tehese constrains, maybe it would be better that we provide a function that adds an input and a reissuance to it, and an output (the token output), rather than expecting them to be already present in the partial transaction and just add a reissuance?

cc @tiero

[tiero]

ACK

[tiero]

Could you split among the tickets you are working on already? @altafan