Add remote timestamps and queue_index to context

This gives us the knobs to expose the remote timestamps and queue_index
to anything receiving the events.  The first use case is the logger.  It
can now log forwarded entries *without* having to make the
message_gateway responsible for logging this data.

Change-Id: Ie34dd040d270f4fa90ecd6e463069e1adca1818a
diff --git a/y2018/control_loops/superstructure/superstructure.cc b/y2018/control_loops/superstructure/superstructure.cc
index 9f5b9fe..f24da3b 100644
--- a/y2018/control_loops/superstructure/superstructure.cc
+++ b/y2018/control_loops/superstructure/superstructure.cc
@@ -289,7 +289,7 @@
     SendColors(0.5, 0.0, 0.0);
   } else if (!vision_status_fetcher_.get() ||
              monotonic_now >
-                 vision_status_fetcher_.context().monotonic_sent_time +
+                 vision_status_fetcher_.context().monotonic_event_time +
                      chrono::seconds(1)) {
     SendColors(0.5, 0.5, 0.0);
   } else if (rotation_state_ == RotationState::ROTATING_LEFT ||