Show number of flights and trains on travel stats page

Closes: #161

templates/trip/stats.html

@@ -28,6 +28,8 @@
       {{ c.flag }} {{ c.name }}
       {% endfor %}
       </div>
+    <div>Flights in {{ year }}: {{ year_stats.flight_count }}</div>
+    <div>Trains in {{ year }}: {{ year_stats.train_count }}</div>
     <div>Total distance in {{ year}}: {{ format_distance(year_stats.total_distance) }}</div>
     {% for transport_type, distance in year_stats.distances_by_transport_type.items() %}
       <div>