message: add constructor Val::Epoch and formatter case which colors it
diff: @@ -24,6 +24,7 @@ pub enum Val<'a> {
  // terminals
  Raw(String),
  Hash(&'a [u8]),
  + Epoch(u32),
  // recursive
  List(Vec<Val<'a>>),
  @@ -56,7 +57,7 @@ fn fmt_val(
  ) -> fmt::Result {
  match val {
  // write terminals inline
  - Val::Raw(_) | Val::Hash(_) => {
  + Val::Raw(_) | Val::Hash(_) | Val::Epoch(_) => {
  write!(f, " ")?;
  fmt_pretty(val, f, indent_size, indent_level)?;
  write!(f, "\n")
  @@ -84,6 +85,7 @@ fn fmt_pretty(
  "{}",
  Colour::Green.paint(wallet_crypto::util::hex::encode(hash))
  ),
  + Val::Epoch(epoch) => write!(f, "{}", Colour::Blue.paint(format!("{}", epoch))),
  // format pretty-val as a set of key-vals
  Val::Tree(ast) => {
  @@ -258,7 +260,7 @@ impl Pretty for normal::Consensus {
  impl Pretty for genesis::Consensus {
  fn to_pretty(&self) -> Val {
  Val::Tree(vec![
  - ("epoch".to_string(), Val::Raw(format!("{}", self.epoch))),
  + ("epoch".to_string(), Val::Epoch(self.epoch)),
  (
  "chain difficulty".to_string(),
  Val::Raw(format!("{}", self.chain_difficulty)),
  