This update for seamonkey fixes the following issues:

Update to SeaMonkey 2.53.21:

  * Unable to load JSON Bookmarks file, Open/Cancel do the same thing
    bug 1940204.
  * Move replaceVars helper into menu-manager.js for cZ bug 1937379.
  * Remove dumpObject helper from utils.js in cZ bug 1937380.
  * Remove toOpenWindowByType helper from utils.js in cZ bug 1937382.
  * Fix makeLogName helper to not encode twice in prefs.js in cZ bug
    1937387.
  * Remove use of escapeFileName helper and tidy up pref_mungeName
    helper in cZ bug 1937395.
  * Add helper to file-utils.js for ensuring an nsIFile is returned in
    cZ bug 1937397.
  * Remove unused http.js file from cZ bug 1937890.
  * Remove unused IRC tests from static.js in cZ bug 1937896.
  * Switch from deprecated escape/unescape in cZ bug 1938933.
  * Tidy up use of prefBranch outside of pref-manager in cZ bug
    1938935.
  * Make use of pref fallbacks in pref-manager in cZ bug 1938937.
  * Remove unused edit context menu from cZ bug 1939929.
  * Use XPCOMUtils.generateQI in connection-xpcom in cZ bug 1939930.
  * Merge menus.xul, popups.xul and scripts.xul into chatzilla.xul bug
    1939958.
  * Make use of toSOutputStream and toSInputStream helpers in DCC code
    in cZ bug 1939965.
  * Stop hard-coding commandkey for reloadui in cZ bug 1939968.
  * Use suite's FillInHTMLTooltip helper instead of having own version
    in cZ bug 1939969.
  * Split custom-away from other away/back commands in cZ bug 1942655.
  * Remove ChatZilla Homepage link from Help menu and about command in
    cZ bug 1942916.
  * Re-arrange toolbar menus in cZ bug 1943783.
  * Remove ChatZilla Homepage link from about and prefs dialogs in cZ
    bug 1943844.
  * Use custom controller for userlist and tidy up some controller use
    in cZ bug 1945325.
  * Make use of observes for show/hide elements in cZ bug 1945378.
  * Don't dynamically create focus-input key element in cZ bug
    1947028.
  * Remove unused toolbar creation code in cZ bug 1947030.
  * Remove unused updateMenus code from cZ bug 1947031.
  * Clean up whitespaces in cZ package manifest bug 1947040.
  * Remove unused uninstallKeys code from cZ bug 1950002.
  * Use node.remove(), especially instead of
    node.parentNode.removeChild(node) in cZ bug 1951250.
  * Remove __cz_condition from cZ bug 1951253.
  * Remove outputWindowURL pref from cZ bug 1951256.
  * Remove unused JS tests in cZ bug 1951297.
  * Use includes, startsWith and endsWith instead of indexOf and
    substr in cZ bug 1951302.
  * Use {} and [] instead of new Object() and new Array() in cZ bug
    1951303.
  * Fixup function naming for lint in cZ bug 1955141.
  * Fixup method naming for lint in cZ bug 1955767.
  * Remove old Mozilla 1.0 code from updateAppMotif in cZ bug 1955771.
  * Use throw Components.Exception in cZ bug 1955774.
  * Migrate output-window from HTML to XHTML to make localisation more
    standard in cZ bug 1955825.
  * Merge munger.js into mungers.js in cZ bug 1956373.
  * Remove unused tagName from mungers.js in cZ bug 1956374.
  * Flatten directory structure in cZ bug 1956375.
  * Tidy up about dialog page in cZ bug 1956376.
  * Add helper to commands.js for sending CTCP commands in cZ bug
    1956377.
  * Migrate to standard menus for menu toolbar in cZ bug 1957763.
  * Install plugin dialog broken in cZ bug 1961599.
  * cZ change nick menu not working bug 1962112.
  * Away status isn't reflected correctly in all channels in cZ bug
    1962234.
  * Fix dark motif userlist in cZ bug 1967072.
  * SeaMonkey Composer adds moz-do-not-send attribute for links and
    images bug 1827146.
  * Use menu_Toolbars overlay for navigatorOverlay and console bug
    1945335.
  * Remove defunct 2.53 prerelease builds from debugQA extension bug
    1947043.
  * Handling of MOZ_LANGPACK_CONTRIBUTORS in defines.inc files should
    be less custom bug 1951101.
  * Control + U shortcut for underlined text is not working bug
    1872514.
  * Context menu search (with default search engine) does not work in
    the content area of a message compose or SM-Composer window bug
    1062092.
  * on FreeBSD sqlite3 fails to link for missing math functions bug
    1944954.
  * Expand init.configure to use version_package.txt to set
    MOZ_PKG_VERSION bug 1952757.
  * Change supported msvc Compilers for SeaMonkey 2.53 bug 1954176.
  * SeaMonkey 2.53.21 uses the same backend as Firefox and contains
    the relevant Firefox 60.8 security fixes.
  * SeaMonkey 2.53.21 shares most parts of the mail and news code with
    Thunderbird. Please read the Thunderbird 60.8.0 release notes for
    specific security fixes in this release.
  * Additional important security fixes up to Current Firefox 115.23
    and Thunderbird 115.23 ESR plus many enhancements have been
    backported. We will continue to enhance SeaMonkey security in
    subsequent 2.53.x beta and release versions as fast as we are able
    to.