0.7.0

Fixed

• PR#20 changed EtherType and IpProto from enums to scoped constants to avoid UB in the presence of invalid/corrupt data that didn't match a variant. Also removed a bunch of the IpProto variants as most will never be used, and since it's now scoped constants users can provide their own constants without needing them in the lib themselves. Resolved #19.
• PR#23 added sanity checks to avoid subtraction underflow if the user provides wildly out of range offsets and/or slices to Packet methods.
• PR#23 fixed a bug in Packet::array_at_offset where the offset was incorrect if head was not 0.
• PR#23 added a check in UdpHeader::parse_packet to ensure the UDP length matches the packet buffer length.

Changed

• PR#22 removed the Index/Mut impls from XskProducer/Consumer as they were unneccessary fluff in favor of much simpler internal methods.
• PR#23 changed data_offset and data_length to just data, a range that is convertible to/from std::ops::Range<usize>. data_length is now a method that just returns data.end - data.start.

Added

• PR#23 added Packet::append as a simpler way to add data to the tail of the packet.
• PR#23 added csum::DataChecksum as a simpler way to calculate the checksum of the data portion of a payload. UdpHeaders::calc_checksum now uses this instead of separate length and checksum arguments.