Bump version to 2.12.4

configure.ac

 dnl Process this file with autoconf to produce a configure script.
 
-AC_INIT([HexChat],[2.12.3])
+AC_INIT([HexChat],[2.12.4])
 
 AC_PREREQ([2.64])
 AC_COPYRIGHT([Copyright (C) 1998-2010 Peter Zelezny])

data/misc/hexchat.appdata.xml.in

@@ -23,6 +23,19 @@
     </screenshot>
   </screenshots>
   <releases>
+    <release date="2016-12-10" version="2.12.4">
+      <description>
+        <p>This is another bug fix release:</p>
+        <ul>
+          <li>Fix issue with timers causing ping timeouts</li>
+          <li>Fix building against OpenSSL 1.1</li>
+          <li>Fix /exec output printing invalid utf8</li>
+          <li>Replace doat plugin with an internal command</li>
+          <li>Change how tab colors interact with plugins</li>
+          <li>Enable filtering the beep character by default</li>
+        </ul>
+      </description>
+    </release>
     <release date="2016-10-22" version="2.12.3">
       <description>
         <p>This is a minor bug fix release just cleaning up a few issues:</p>