message: rename field accessor
diff: @@ -19,7 +19,7 @@ impl From<Slot> for u64 {
  pub struct SlotAndDuration {
  pub slot: Slot,
  /// The offset of a specific time frame in
  - pub slot_duration_offset: Duration,
  + pub offset: Duration,
  }
  /// Time frame which is a timeline that is configured to be split in discrete slots
  @@ -102,7 +102,7 @@ impl TimeFrame {
  let d = t.0 - Duration::from_secs(e); // cannot wrap
  Some(SlotAndDuration {
  slot: Slot(self.slot_offset.0 + slot_nb),
  - slot_duration_offset: d,
  + offset: d,
  })
  }
  }
  