RecycleSlice zeroes byte slice, making it fresh for another use.

ReadSize represents the size of the maximum message that can be read off the wire by brontide.

WriteSize represents the size of the maximum plaintext message than can be sent using brontide.

Read is a static byte array sized to the maximum-allowed Lightning message size, plus 16 bytes for the MAC.

Write is static byte array occupying to maximum-allowed plaintext-message size.