Doesn't support raw ident

[nhynes]

The following works in quote but fails in proc_quote:

#[test]
fn test_raw_ident() {
    quote!( r#the );
}

with the error

thread 'main' panicked at '"r#the" is not a valid Ident'
stack backtrace:
   7: proc_macro2::fallback::validate_term
   8: proc_macro2::fallback::Ident::_new
   9: proc_macro2::fallback::Ident::new
  10: proc_macro2::imp::Ident::new
  11: proc_macro2::Ident::new
  12: proc_quote::__rt::append_ident

[nhynes]

related: dtolnay/proc-macro2#140

[Goncalerta]

Thanks a lot for the report.
Just fixed it in 60bd96e.

[nhynes]

Thanks a lot for the quick fix!