Add drivetrain replay application

This adds a basic example application for replaying the 2019 drivetrain.

I also make it so that the LogReader will stop event processing once it
is done.

Change-Id: Icd0187f240191b8d23e31608eb6e5a5a49fd068c
diff --git a/y2019/control_loops/drivetrain/BUILD b/y2019/control_loops/drivetrain/BUILD
index 1575584..bc76d7a 100644
--- a/y2019/control_loops/drivetrain/BUILD
+++ b/y2019/control_loops/drivetrain/BUILD
@@ -214,3 +214,21 @@
         "//frc971/control_loops/drivetrain:drivetrain_test_lib",
     ],
 )
+
+cc_binary(
+    name = "drivetrain_replay",
+    srcs = ["drivetrain_replay.cc"],
+    data = ["//y2019:config.json"],
+    deps = [
+        ":drivetrain_base",
+        ":event_loop_localizer",
+        "//aos:configuration",
+        "//aos:init",
+        "//aos/events:shm_event_loop",
+        "//aos/events:simulated_event_loop",
+        "//aos/events/logging:logger",
+        "//frc971/control_loops/drivetrain:drivetrain_lib",
+        "@com_github_gflags_gflags//:gflags",
+        "@com_github_google_glog//:glog",
+    ],
+)