Initial messages design from this week
Remove script/ directory (out-of-date)
Make number structs copyable
Completes basic packet processing functionality.

`rust-dns` can process complete DNS packets.

Test suite includes test packets captured live using Wireshark
for verification.

TODO: Clean up codebase.
Add test client note to README [skip ci]
Merge pull request #6 from oko/feature-messages

Well, that's an improvement.