Macro loggy::note

macro_rules! note {
    ($is_error:expr, target: $target:expr, $($arg:tt)*) => { ... };
    ($is_error:expr, $($arg:tt)*) => { ... };
}

Generate either an error or a warning, depending on some configuration parameter.

Invoking note!(is_error, ...) is identical to invoking error! if is_error is true, or warn! if is_error is false. This allows easily handling conditions whose handling depends on command line arguments or other considerations.