new settings panel for url pickup

lib/app.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:mileograph_flutter/services/api_service.dart';
 import 'package:mileograph_flutter/services/authservice.dart';
 import 'package:mileograph_flutter/services/data_service.dart';
+import 'package:mileograph_flutter/services/endpoint_service.dart';
 import 'package:mileograph_flutter/ui/app_shell.dart';
 import 'package:provider/provider.dart';
 
@@ -12,8 +13,16 @@ class App extends StatelessWidget {
   Widget build(BuildContext context) {
     return MultiProvider(
       providers: [
-        Provider<ApiService>(
-          create: (_) => ApiService(baseUrl: 'https://mileograph.co.uk/api/v1'),
+        ChangeNotifierProvider<EndpointService>(
+          create: (_) => EndpointService(),
+        ),
+        ProxyProvider<EndpointService, ApiService>(
+          update: (_, endpoint, api) {
+            final service = api ?? ApiService(baseUrl: endpoint.baseUrl);
+            service.setBaseUrl(endpoint.baseUrl);
+            return service;
+          },
+          create: (_) => ApiService(baseUrl: EndpointService.defaultBaseUrl),
         ),
         ChangeNotifierProvider<AuthService>(
           create: (context) => AuthService(api: context.read<ApiService>()),