doxygen: remove unreplaced variables from custom header and footer

doc/doxy/footer.html

  </div>
 
  <div id="footer">
- <!--BEGIN GENERATE_TREEVIEW-->
-     <li class="footer">$generatedby
-     <a href="http://www.doxygen.org/index.html">
-     <img class="footer" src="doxygen.png" alt="doxygen"/></a> $doxygenversion </li>
-    </ul>
- <!--END GENERATE_TREEVIEW-->
- <!--BEGIN !GENERATE_TREEVIEW-->
- <address class="footer"><small>
- $generatedby &#160;<a href="http://www.doxygen.org/index.html">
- <img class="footer" src="$relpath$doxygen.png" alt="doxygen"/>
- </a> $doxygenversion
- </small></address>
- <!--END !GENERATE_TREEVIEW-->
+   Generated on $datetime for $projectname by&#160;<a href="http://www.doxygen.org/index.html">doxygen</a> $doxygenversion
  </div>
 
 </div>

doc/doxy/header.html

@@ -6,9 +6,6 @@
 <!--BEGIN PROJECT_NAME--><title>$projectname: $title</title><!--END PROJECT_NAME-->
 <!--BEGIN !PROJECT_NAME--><title>$title</title><!--END !PROJECT_NAME-->
 <link href="$relpath$doxy_stylesheet.css" rel="stylesheet" type="text/css" />
-$treeview
-$search
-$mathjax
 </head>
 
 <div id="container">