RVW-1: licence references keep their leading zeros

Several registers issue references with leading zeros, letters, slashes or spaces. Any implementation that reads one into an integer loses information and will match the wrong licence sooner or later.

RVW-1 section 3 now says it in the field table: the reference is carried exactly as the authority writes it. Since the canonical form forbids floating point values anyway, nothing in a claim should ever be parsed as a number except the document version.