Add output to the lockStates() function

[jimthematrix]

Feedback from @awrichar: If I have a single Zeto coin worth 100, but I want to lock 1, is there a way to make that possible with a single transaction (similar to what I've done for Noto)? Otherwise, I'll end up locking my entire large coin just to transfer a small bit of it.

[awrichar]

Note: While this is a separate question, it may roll into the wider discussion around locking and UTXOs as part of #119