bug#56514: 29.0.50; Improve ERC's URI scheme integration for irc:// links

[J.P.]

v4.

- Dropped the request-tracking POC stuff because those patches only
  benefit the Org integration, which needs special attention anyway.

- Added unifying changes to url-irc and browse-url that treat ERC and
  rcirc equally.


Questions (for anyone):

  1. I added a couple autoloads in lisp/url/url-irc.el to avoid having
     to create a url-ircs.el (or even a url-irc6{,s}.el). Is there a
     better alternate means of getting `url-scheme-get-property' to
     discover handlers that doesn't rely on autoloads?

  2. In the function `url-irc', I bind `url-current-object' around the
     call to `url-irc-function' to avoid adding another parameter to the
     latter's interface (which mainly benefits ERC). Any obvious problem
     with borrowing `url-current-object' for this purpose?

  3. In browse-url, I basically ignore what looks like the favored
     practice for adding handlers, namely, registering an internal
     function with `browse-url-default-handlers' that calls a public
     function assigned to a user option. An example of this pattern is:

       internal: browse-url--mailto
       option:   browse-url-mailto-function
       public:   browse-url-mail

     The reason for sidestepping the intervening indirection and adding
     a public function directly to `browse-url-default-handlers' is that
     I figure users wishing to override this can already do so via
     `browse-url-handlers'. Is that misguided somehow?

  4. Are any of these non-ERC changes newsworthy enough for etc/NEWS?

Thanks!

0000-v3-v4.diff
Description: Text Data

0001-Teach-thing-at-point-to-recognize-bracketed-IPv6-URL.patch
Description: Text Data

0002-Accommodate-ircs-URLs-in-url-irc-and-browse-url.patch
Description: Text Data

0003-Refactor-erc-select-read-args.patch
Description: Text Data

0004-Default-to-TLS-port-when-calling-erc-tls-from-lisp.patch
Description: Text Data

0005-Add-optional-server-param-to-erc-networks-determine.patch
Description: Text Data

0006-Improve-new-connections-in-erc-handle-irc-url.patch
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