[Python-Dev] Improve open() to support reading file starting with an unicode BOM

["Martin v. Löwis"]

> But an autodetect feature is not a codec. Sure it should be reusable,
> but making it a codec seems to be  a weird hack to me.

Well, the existing UTF-16 codec also is an autodetect feature (to
detect the endianness), and I don't consider it a weird hack.

Regards,
Martin