export and import of xdr mappings

web/index.html

@@ -65,6 +65,8 @@
     <button id="resetForm">ReloadConfig</button>
     <button id="changeConfig">Save&Restart</button>
     <button id="loadUnassigned">Show Unmapped</button>
+    <button id="exportXdr">Export</button>
+    <button id="importXdr">Import</button>
   </div>
 </div>
 <div class="tabPage hidden" id="dashboardPage">
@@ -113,6 +115,9 @@
     in the documentation.
   </p>  
 </div>
+<div class="hidden">
+  <a id="downloadXdr"></a>
+</div>
 </body>
 </html>