message: New variant of `add_unit!` macro.
  Allows for creating units with endorsed hashes.
diff: @@ -17,6 +17,9 @@ macro_rules! panorama {
  /// automatically picks reasonable values for those.
  macro_rules! add_unit {
  ($state: ident, $rng: ident, $creator: expr, $val: expr; $($obs:expr),*) => {{
  + add_unit!($state, $rng, $creator, $val; $($obs),*;)
  + }};
  + ($state: ident, $rng: ident, $creator: expr, $val: expr; $($obs:expr),*; $($ends:expr),*) => {{
  #[allow(unused_imports)] // These might be already imported at the call site.
  use crate::{
  components::consensus::highway_core::{
  @@ -64,7 +67,7 @@ macro_rules! add_unit {
  seq_number,
  timestamp,
  round_exp,
  - endorsed: std::collections::BTreeSet::new(),
  + endorsed: vec![$($ends),*].into_iter().collect(),
  };
  let hash = wunit.hash();
  let swunit = SignedWireUnit::new(wunit, &TestSecret(($creator).0), &mut $rng);
  