Implement an initial SMIv2 parser based around RFC257[89]. RFC2580 isn't

Implement an initial SMIv2 parser based around RFC257[89]. RFC2580 isn't
supported yet. SMIv1 is not supported. Parsing is done in a strict
manner, but except for the (deprecated) IPV6-TC MIB everything from
IETF/IANA that I found parses.

For now this code will be used OID<->name translations, but other
functionality could be added in the future.

This commit just includes the parser, usage and including the MIB files
will be done in separate commits.

Go ahead from tb@