* 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/url/url-util.el (url-domain): Add an example to the doc
string.

* lisp/url/url-util.el (url-domain): Don't talk DNS to determine
the domain, because this is slow.

* test/lisp/url/url-util-tests.el (url-domain-tests): Add tests
for `url-domain'.

* lisp/url/url-http.el (url-http-create-request): Ensure that the
entire request string is unibyte (bug#31248).

* lisp/url/url-cookie.el (url-cookie-undo): New command and
keystroke (bug#16650).

* lisp/url/url-cookie.el (url-cookie--generate-buffer): Factor out
into its own function.
(url-cookie-delete): Use it to make the buffer look consistent
after deleting a cookie.

* lisp/url/url-cookie.el (url-cookie-write-file): If
`url-cookie-file' isn't set (due to url.el not being used yet),
don't error out in this function (bug#23183).

* doc/misc/url.texi (file/ftp): Remove mention of the
url-directory-index-file variable, which is no longer consulted.

* lisp/url/url-file.el (url-file-build-filename): Remove the DWIM
code from the file: handler (bug#30195): It would look for
index.html in a directory if we asked it to fetch the directory.
Determining what to do in a directory should be left up to the
programs that use this low-level library.  If the library decides
to load a different file than we specified, then things start
falling apart, as demonstrated by this bug report.