Revert "Use double instead of timestamp"

This reverts commit 0d62da8.

protos/farm_ng/core/recorder.proto

@@ -15,6 +15,7 @@
 syntax = "proto3";
 
 import "farm_ng/core/event_service.proto";
+import "farm_ng/core/timestamp.proto";
 
 package farm_ng.core.proto;
 
@@ -36,7 +37,7 @@ message RecorderProfile {
 // A message that can be used to live annotate a recording.
 
 message RecorderAnnotation {
-    double stamp = 1; // The timestamp of the annotation.
+    Timestamp stamp = 1; // The timestamp of the annotation.
     AnnotationKind kind = 2; // The kind of annotation.
     string message = 3; // An optional message of the annotation. E.g., "Start of row 1".
 }