Log Message:
Update devel/fossil to 2.19

## Changes for version 2.19 (2022-07-21)
  *  On file listing pages, sort filenames using the "uintnocase" collating
     sequence, so that filenames that contains embedded integers sort in
     numeric order even if they contain a different number of digits.
     (Example:  "fossil_80_..." comes before \ 
"fossil_100.png" in the
     [/dir?ci=92fd091703a28c07&name=skins/blitz|/skins/blitz] directory listing.)
  *  Enhancements to the graph layout algorithm design to improve readability
     and promote better situational awareness.
  *  Performance enhancement for the
     [./checkin_names.wiki#root|"root:BRANCHNAME" style of tag],
     accomplished using a Common Table Expression in the underlying SQL.
  *  Sort tag listings (command line and webpage) by taking numbers into
     consideration so as to cater for tags that follow semantic versioning.
  *  On the wiki listings, omit by default wiki pages that are associated with
     check-ins and branches.
  *  Add the new "[/help?cmd=describe|fossil describe]" command.
  *  Markdown subsystem extended with [../src/markdown.md#ftnts|footnotes support].
     See corresponding [../test/markdown-test3.md|test cases],
     [/wiki?name=branch/markdown-footnotes#il|known limitations] and
     [forum:/forumthread/ee1f1597e46ec07a|discussion].
  *  Add the new special name "start:BRANCH" to refer to the first \ 
check-in of
     the branch.
  *  Support [/wiki?name=branch/generated-tkt-mimetype&p|generated \ 
"mimetype"]
     columns in the <var>TICKET</var> and \ 
<var>TICKETCHNG</var> tables.
  *  Fix [/timeline?r=fix_remote_url_overwrite_with_proxy|remote-url-overwrite]
     bug where remote-url is overwritten by the proxy setting during sync
     operation. Also require explicit "system" proxy setting to use
     "http_proxy" environment variable.
  *  Reimplemented the [/pikchrshow] app to use a WebAssembly build of
     pikchr so that it can render pikchrs on the client instead of requiring
     a server round-trip.
  *  Add the [/help?cmd=email-listid|email-listid setting]. If set, it is
     used as the List-ID header for all outbound notification emails.
  *  Add the "--branch" option to the \ 
"[/help?cmd=timeline|timeline]" command
     to restrict the displayed items to a specific branch.
  *  Add the "--versions" option to "[/help?cmd=diff|fossil \ 
diff]"
     to display details about the compared versions into the patch header.
  *  Numerous other minor enhancements.