It appears the pinned attrset is a bit adhoc. This generalizes
pinned.nix so that you can do:
$ nix build -f . pinned.stable.hwi
$ nix build -f . pinned.unstable.hwi
etc
Signed-off-by: William Casarin <jb55@jb55.com>
Disabling upnp via compilation brings no substantial security benefits.
There's no way to inadvertently enable upnp, it must be set explicitly
via bitcoind.extraConfig.
But it's a huge hassle for new users who have to recompile bitcoind
before being able to use nix-bitcoin.
Also, elementsd is currently built with upnp support by default.
