Refreshed BIP324

Pieter Wuille suggests merging short and long command structures into a single variable-length command structure with 1-12 byte encodings where the top bit of each byte indicates whether another byte follows. This creates a uniform space for assigning commands, eliminating the need to treat short-binary and long-alphabetic commands as distinct. In version 2, some short commands would be treated as aliases for old long-alphabetic ones. While reversing the meaning of the top bit to interpret alphabetic commands as non-alphabetic seems dubious, it eliminates the need for disjoint sub-spaces. However, this method does not reassign shorter codes or consider that numerical values may exceed 85-86 bits. Yet, as there are no collisions in the first 9 bytes of existing commands, constraining the non-alphabetic representation to 9 bytes leaves the last top bit free, resulting in an isomorphic space to {0,1}^64.