prepare for custom wallpaper listing editor

preferences.html

@@ -112,12 +112,11 @@
     <div id="custom-wallpapers-wrapper" class="settings-container">
         <div class="setting-container">
             <input type="checkbox" name="enable-custom-wallpapers-check" id="enable-custom-wallpapers-check">
-            <label for="enable-custom-wallpapers-check">Enable custom wallpapers (extremely experimental)</label>
+            <label for="enable-custom-wallpapers-check">Enable custom wallpapers</label>
         </div>
         <div class="setting-container">
-            <label for="custom-wallpapers-array-input">Array of custom wallpapers:</label>
-            <textarea cols="30" rows="1" placeholder="[&#34;image1.url&#34;, &#34;image2.url&#34;]"
-                name="custom-wallpapers-array-input" id="custom-wallpapers-array-input"></textarea>
+            <input type="text" name="new-wallpaper-to-add" id="add-wallpaper-input" placeholder="New wallpaper link">
+            <button id="add-wallpaper-button">add wallpaper</button>
         </div>
     </div>
     <!--