Organised dom cache

Moved change listeners to document level
Added gain
Option to combine local bird filter with new notcurnal caller filter

Help/settings.html

@@ -108,7 +108,11 @@
         </td>
     </tr>
     <tr>
-        <td colspan="2" class="text-center text-bg-light"><h5>Audio Export Preferences</h5></td>
+        <td colspan="2" class="text-center text-bg-light"><h5>Audio Preferences</h5></td>
+    </tr>
+    <tr>
+        <td><b>Gain Adjustment</b></td>
+        <td>If your recordings are very quiet, you can increase the loudness of the audio by adding gain. The volume of audio can be increased by up to 50 decibels.</td>
     </tr>
     <tr>
         <td><b>Format and Bitrate</b></td>
@@ -151,7 +155,7 @@
     </tr>
 
     <tr>
-        <td colspan="2" class="text-center text-bg-warning"><h5>Experimental Features</h5></td>
+        <td colspan="2" class="text-center text-bg-warning"><h5>Advanced Features</h5></td>
     </tr>
     <tr>
         <th>Context Mode</th>