reworked page layout inheritence

frontend/lib/pages/new_trip_preferences.dart

@@ -1,5 +1,5 @@
+import 'package:anyway/layouts/scaffold.dart';
 import 'package:anyway/modules/new_trip_button.dart';
-import 'package:anyway/pages/base_page.dart';
 import 'package:anyway/structs/preferences.dart';
 import 'package:anyway/structs/trip.dart';
 import 'package:flutter/cupertino.dart';
@@ -15,13 +15,14 @@ class NewTripPreferencesPage extends StatefulWidget {
   _NewTripPreferencesPageState createState() => _NewTripPreferencesPageState();
 }
 
-class _NewTripPreferencesPageState extends State<NewTripPreferencesPage> {
+class _NewTripPreferencesPageState extends State<NewTripPreferencesPage> with ScaffoldLayout {
   UserPreferences preferences = UserPreferences();
 
   @override
   Widget build(BuildContext context) {
-    return BasePage(
-      mainScreen: Scaffold(
+    return mainScaffold(
+      context,
+      child: Scaffold(
         body: ListView(
           children: [
             // Center(
@@ -41,23 +42,22 @@ class _NewTripPreferencesPageState extends State<NewTripPreferencesPage> {
             //   )
             // ),
 
-            Center(
-              child: Padding(
-              padding: EdgeInsets.only(left: 10, right: 10, top: 20, bottom: 0),
-                child: Text('Tell us about your ideal trip.', style: TextStyle(fontSize: 18))
-              ),
+          Center(
+            child: Padding(
+            padding: EdgeInsets.only(left: 10, right: 10, top: 20, bottom: 0),
+              child: Text('Tell us about your ideal trip.', style: TextStyle(fontSize: 18))
             ),
+          ),
 
-            Divider(indent: 25, endIndent: 25, height: 50),
+          Divider(indent: 25, endIndent: 25, height: 50),
 
-            durationPicker(preferences.maxTime),
+          durationPicker(preferences.maxTime),
 
-            preferenceSliders([preferences.sightseeing, preferences.shopping, preferences.nature]),
-          ]
-        ),
-        floatingActionButton: NewTripButton(trip: widget.trip, preferences: preferences),
+          preferenceSliders([preferences.sightseeing, preferences.shopping, preferences.nature]),
+        ]
+      ),
+      floatingActionButton: NewTripButton(trip: widget.trip, preferences: preferences),
       ),
-      
       title: FutureBuilder(
         future: widget.trip.cityName,
         builder: (context, snapshot) => Text(