* lisp/obsolete/tls.el: Moved from lisp/net/tls.el.
* lisp/gnus/nnimap.el:
* lisp/url/url-http.el: Don't require tls, since it's obsolete.
* lisp/net/network-stream.el: Only require tls if we actually try to
use it (i.e., when (gnutls-available-p) returns nil). Declare some
functions to fix compilation warnings.
* lisp/obsolete/starttls.el: Moved from lisp/net/starttls.el.
* lisp/net/sieve-manage.el:
* lisp/net/network-stream.el: Don't require `starttls' at the
top-level, declare the variables and functions used instead.
(network-stream-open-starttls): Only require `starttls' if
needed (i.e., gnutls-available-p fails).
* etc/NEWS: Announce obsoletion.
* lisp/net/pop3.el: Use lexical-binding and cl-lib.
(pop3-write-to-file): Remove unused var 'start'.
(pop3-make-date): Remove unused var 'sign'.
* lisp/net/rfc2104.el: Use lexical-binding and cl-lib.
* lisp/net/shr-color.el: Use lexical-binding and cl-lib.
* lisp/net/sieve-manage.el: Use lexical-binding and cl-lib.
Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November. Change these FTP URLs to https://ftp.gnu.org
instead. Make similar changes for URLs to other organizations moving
away from FTP. Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.
* lisp/net/sieve-manage.el (sieve-manage-ignore-starttls):
Rename from sieve-manage-ignore-broken-tls. If it is set,
sieve-manage will never use STARTTLS even if the server says
it is capable (but may be broken).
* lisp/net/sieve-manage.el
(sieve-manage-ignore-broken-tls): New user option.
(sieve-manage-open-server):
Don't test STARTTLS capability if the option is set (bug#24422).
