/// svec! makes a string vector from an array of &str.
///
/// Example:
///
/// ```
/// use usv::svec;
/// let items = svec!["a", "b", "c"];
/// assert_eq!(
/// items,
/// vec![
/// String::from("a"),
/// String::from("b"),
/// String::from("c"),
/// ]
/// );
/// ```
///
;