Fixes: debbugs:19149

* gtkutil.c (gtk_adjustment_configure): Don't use 2.14 functions (Bug#19149).
Add functions to gnutls.c for exporting certificate details

* gnutls.c (gnutls_hex_string, gnutls_certificate_details)
(Fgnutls_peer_status): New functions to export TLS certificate
details to Emacs Lisp.

* process.h: Added more fields to Lisp_Process to track
certificate details.

* gnutls.c (Fgnutls_boot): Save certificate for later inspection.
Implement a Network Security Manager

* processes.texi (Network): Mention the new :warn-unless-encrypted
parameter to `open-network-stream'.
(Network): Mention the Network Security Manager.

* net/nsm.el: New file that implements a Network Security Manager.

* net/network-stream.el (open-network-stream): Add a new
:warn-unless-encrypted parameter.
(network-stream-open-plain): Allow warning unless encrypted.
(network-stream-open-starttls): Call the Network Security Manager.
(network-stream-open-tls): Ditto.
Make some network connections warn unless they are encrypted

* mail/smtpmail.el (smtpmail-via-smtp): Warn unless encrypted and
we're sending a password.

* pop3.el (pop3-open-server): Warn unless encrypted.

* nnimap.el (nnimap-open-connection-1): Warn unless encrypted.
Implement a new url parameter `url-request-noninteractive'

* url-http.el (url-http): Respect `url-request-noninteractive'.

* url-queue.el (url-queue-start-retrieve): Fetching through
url-queue should always be noninteractive.

* url-vars.el (url-request-noninteractive): New variable.
Rename `nsm-security-level' to `network-security-level'

* net/nsm.el (network-security-level): Rename from
`nsm-security-level' and documented.