Multiple OpenPGP keys

It would be nice to be able to manage multiple public keys and identities on one account.

Rationale: Often you have multiple keys that belong to you, split by various purposes. Thus while key A might be my primary one for "default mail" you will occasionally see some other keys B and C used. Currently I don't see how to get this onto my account.

P.S.: Same goes for domains, email addresses and social media accounts.

The issue names no files, tests, or entry points. Start by locating the account identity and key-management areas; done means one account can manage multiple public keys and identities, with the same support considered for domains, email addresses, and social media accounts.

Written by the indexing model from the issue text.