Wildcards have been replaced with what is actually used.
In a couple of cases an additional use statement was added to the test
module to import `DisplayHex` which is only used in test, but
previously imported with the wildcard at the top.
BIP324's peer to peer encryption protocol requires an HMAC-based extract
and expand key derivation function (HKDF). HKDFs were not part of many
bitcoin protocols before BIP324, but the hope is that the encrypted
protocol becomes the dominant standard justifying this implementation.