macvlan interfaces never directly exchange traffic with the underlying
interface, but only with other hosts behind the interface. In consequence,
router advertisements from the uradvd running on br-client could never
reach local-node, preventing it from getting an IPv6 address without RAs
from an external radvd. Fix this be replacing the macvlan interface with
a veth pair (with the peer interface in br-client).

As a side effect, this saves about 5KB of flash, as the veth module is
simpler than macvlan.

Prepare reverting the roles of br-client and local-node to their state
before 8c4403ba.

This package provides br-client and sets up a wireless AP interface for
clients.

This package will run as invariant script after each upgrade and copy
all keys from site.conf's authorized_keys entry to
/etc/dropbear/authorized_keys.

Existing keys will be preserved.

The site.conf entry 'authorized_keys' is required (if this package is
selected) and must contain a list of strings, each representing a line
of the resulting file.