Initial implementation of 'next arrivals'. Needs more work.

src/gtfs/structs.rs

@@ -8,9 +8,10 @@ pub struct Preferences {
     pub stop_codes: HashSet<String>,
 }
 
+#[derive(Debug)]
 
 pub struct Arrival<'a> {
     pub route: &'a Route,
     pub stop: &'a Stop,
-    pub timepoint: &'a TimepointType,
+    pub departure_time: u32,
 }