Brings the most relevant types and traits into scope for working with packets.
Less often used types and traits that are more likely to lead to a
naming conflict are not brought into scope. For instance, the
PublicParts, etc. are not imported to avoid potential
naming conflicts. Instead, they should be accessed as
user_attribute::Subpacket is not
imported, because it is rarely used. If required, it should be
Holds a compressed data packet.
Holds packet bodies.
Holds a literal packet.
Holds an MDC packet.
Holds a Marker packet.
Holds a Trust packet.
Holds an unknown packet.
Holds a UserID packet.
A packet's body holds either unprocessed bytes, processed bytes, or packets.
The OpenPGP packet tags as defined in Section 4.3 of RFC 4880.