XLS-64d pseudo-account

[Tapanito]

The discussion for this specification can be found here: #191

[ximinez]

I think section "2.1.3 Cost" should be updated to say something like:

A pseudo-account must increase the owning / controlling account's reserve by 1 in addition to any increases required by the creation of other objects. A transaction that creates a pseudo-account that is not owned or controlled by the creating account must incur a higher-than-usual transaction fee to deter ledger spam, and must destroy at least the incremental owner reserve amount, currently 0.2 XRP.

I believe this spec was written based on the experiences with AMM.

From #240 (comment)

AMMCreate doesn't increase anyone's owner count, partly because the object isn't owned by anyone once it's created, but that's the point - the fee is partly high because there's no one to require a reserve from.

In the case of other objects like Vault or LoanBroker where there is an account that effectively owns and controls the created-pseudo-account I think it makes way more sense to increase the owner count by 2 (1 for the pseudo-account, and 1 for the vault or broker object), and charge a normal transaction fee.

As a ledger object, there is nothing special or unusual about a pseudo-account if it has a single, defined owner. It's not unusually large. It doesn't function independently. It's just needed as a placeholder to allow other objects to work properly.

(Copied from #191 (comment))