message: avoid one alocation when calling concat_elements
diff: @@ -54,11 +54,10 @@ macro_rules! format_elements {
  ( $( $element:expr ),+ $(,)?) => {{
  use $crate::{FormatElement, concat_elements};
  - concat_elements(vec![
  + concat_elements([
  $(
  FormatElement::from($element)
  ),+
  -
  ])
  }};
  }
  