Macro impl_parse

macro_rules! impl_parse {
    ($type:ty, $descr:expr, $func:expr, $vis:vis $error:ident, $error_source:ty $(, $error_derive:path)*) => { ... };
}

Implements conversions from various string types.

This macro implements FromStr as well as TryFrom<{stringly} where {stringly} is one of these types:

• &str
• String
• Box<str>
• Cow<'_, str>

The last three are only available with alloc feature turned on.