This commit makes NM code to report HTTP as a stream protocol. This
makes it possible to handle large responses properly. Like:
dig +https @127.0.0.1 A cmts1-dhcp.longlines.com
* The location of the digest type field has changed to where the
reserved field was.
* The reserved field is now called scheme and is where the digest
type field was.
* Digest type 2 has been defined (SHA256).
The transport should also be detached when we skip a master, otherwise
named will crash when sending a SOA query to the next master over TLS,
because the transport must be NULL when we enter
'dns_view_gettransport'.
