list traction and add leaderboard panel

lib/components/pages/traction.dart

@@ -0,0 +1,23 @@
+import 'package:flutter/material.dart';
+import 'package:mileograph_flutter/objects/objects.dart';
+import 'package:provider/provider.dart';
+import 'package:mileograph_flutter/services/dataService.dart';
+
+class TractionPage extends StatelessWidget {
+  Widget build(BuildContext context) {
+    final data = context.watch<DataService>();
+    return ListView.builder(
+      itemCount: data.traction.length,
+      itemBuilder: (context, index) {
+        final loco = data.traction[index];
+        return Card(
+          margin: EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+          child: Padding(
+            padding: EdgeInsets.all(16),
+            child: Text('${loco.locoClass} ${loco.locoNumber}'),
+          ),
+        );
+      },
+    );
+  }
+}