Fix & linkify JavaDoc
Improve FCP field naming of identitiy stuff:
- To complete the changes to score/trust two commits ago (8e5b831d0845a371d18ed4b6959747d99f3ce9b9)
- Instead of "Nickname" use "Identity.0.Value". Do this to all identity fields
- Instead of "Amount" use "Identities.Amount"
- Specify the amount when sending only a single identity
- Part of the API is present on master, part is not. So we can only add fields, not rename the ones which are used on master. I tried to make very sure to not break anything.