[RT #2394]

Basically, "freeze" disables dynamic updates to a zone, syncs the journal
file into the master file, and removes the journal.  This allows manual
edits of a dynamic zone file without stopping the server, since the
zone is temporarily considered non-dynamic.  "unfreeze" re-enables dynamic
updates to a zone.

So, instead of the old:
	rndc stop
	edit master file
	remove journal
	restart server
you can now do:
	rndc freeze zone
	edit master file
	rndc reload zone
	rndc unfreeze zone
which doesn't require stopping the server.

About everyone here at the secure dynamic update workshop wanted this.
It will be documented soon.