Config-file lines consist of a keyword and data.  The keyword consists
of everything from the first non-whitespace character to the next
whitespace character, or the end of line if there is no following
whitespace character.  If there are no non-whitespace characters at
all, or if the first such is a #, the line is a comment and is ignored.

The data begins with the first non-whitespace character after the
keyword.  (This implies it cannot begin with whitespace.)

@ FILE
	FILE is read and its contents effectively inserted in place of
	this line.

key KEY
	The cloud key is literally KEY.

keyfile KEYFILE
	KEYFILE is read and the contents are the cloud key.  If the
	file is larger than 64K, only the first 64K is used.

id N
	This member's cloud ID is N; N must be in 0..255.

ip ADDR
	ADDR is one of this member's cloud IPs.  This may be given
	multiple times; the resulting addresses accumulate.

type T
	This member's type is T.  T can be

		public	This cloud member is type 1 or type 2.  If any
			`listen' lines are given, it's type 1;
			otherwise, it's type 2.

		private	This cloud member is type 3.

listen ADDR/PORT
	This host is type 1 and should listen on ADDR/PORT for cloud
	connections.  This may be given multiple times to listen on
	multiple endpoints.  The special strings *, *4, and *6 may be
	given for ADDR to listen on all local addresses, all local IPv4
	addresses, and all local IPv6 addresses, respectively.

uplink ADDR/PORT
	For a type 1 or 2 host, this is an initial entry point into the
	public cloud.  For a type 3 host, this is a type 1 or 2 uplink
	host (presumably on a private IP, but this is not actually
	required).  This can be given multiple times, and the contact
	points accumulate.