feat(interface-types) InterfaceValue::Record now takes a Vec1.

It matches the definition of `InterfaceType::Record`.

src/macros.rs

@@ -1,6 +1,8 @@
+//! Collection of helpful macros.
+
 /// This macro creates a `Vec1` by checking at compile-time that its
 /// invariant holds.
-#[allow(unused)]
+#[macro_export]
 macro_rules! vec1 {
     ($item:expr; 0) => {
         compile_error!("Cannot create an empty `Vec1`, it violates its invariant.")