Fix non-implied-OID-to-index conversion (#98)
Fix non-implied-OID-to-index conversion (#98)

Non-implied OIDs, when laid in index, should be prefixed with the length
of the OID, but the current code erroneously uses len(self.name), that
is, the length of the MibTableRow's name instead.
etingof/pysnmp,etingof/pysnmp