[Maintain] labels at the top of a domain

[Dawn Keenan]

While I was looking into importing the 50-something small domains we
still manage by hand into Maintain 3.1, I rediscovered one of the
reasons I hadn't put those domains under Maintain when we moved from
locally-written DNS management tools to Maintain 2.x:  data at the top of
the zone, whose parent we don't own.

For example, the domain 'alzheimersresearchexchange.ca' contains both A
(host) and MX (mail exchange) records at the top level.  In BIND syntax,
I would use the label '@' for those records in the data file for the
domain; I don't know how djbdns/tinydns handles such data (I could
spend more time reading http://cr.yp.to/djbdns/run-server-bind.html,
where djb describes how to combine some record types).

Maintain 3.1 currently doesn't allow data at the top of a zone unless
the parent zone is also in Maintain.  My personal preference would be to
allow the use of an '@' label (I'm familiar and comfortable with) in MX
and host records by administrators with "system admin" privileges, but
there may be a better solution.

--Dawn