peer: use a dedicated name for the `peer` constructor We want to change the argument it takes, so we rather make them different function.

peer: dissolve `_peerlookup` into its last two callers This is about to need more changes and the function won't be useful. We do it early to clarify later changes.

peer: stop having a `peer()` method on `peer()` This is already a peer, why do you want a peer if you already have one.