associated backend fixes

frontend/lib/pages/new_trip_preferences.dart

@@ -63,7 +63,7 @@ class _NewTripPreferencesPageState extends State<NewTripPreferencesPage> {
       margin: const EdgeInsets.only(left: 10, right: 10, top: 10, bottom: 0),
       shadowColor: Colors.grey,
       child: ListTile(
-        leading: Icon(Icons.timer),
+        leading: preferences.maxTime.icon,
         title: Text(preferences.maxTime.description),
         subtitle: CupertinoTimerPicker(
           mode: CupertinoTimerPickerMode.hm,

frontend/lib/pages/settings.dart

@@ -61,9 +61,7 @@ class _SettingsPageState extends State<SettingsPage> {
                     return AlertDialog(
                       title: Text('Debug mode - use a custom API endpoint'),
                       content: TextField(
-                        decoration: InputDecoration(
-                          hintText: 'https://anyway-stg.anydev.info'
-                        ),
+                        controller: TextEditingController(text: API_URL_DEBUG),
                         onChanged: (value) {
                           setState(() {
                             API_URL_BASE = value;