0.8.0

• Bump MSRV to 1.58.0 (#31)
• #[autoimpl(Clone, Debug, PartialEq, Eq, Hash)] now all support enums
  (with optional where clause, without ignore clauses) (#31)
• Add impl_tools_lib::ImplTrait::enum_impl, enum_items with default impls;
  ImplTraits::expand now supports enums (#31)
• Add impl_tools_lib::Ident_formatter utility (#31)

Note: PartialOrd, Ord could now support enums (unimplemented). ignore and
using clauses are deliberately not supported (due to syntactic ambiguity).