Changed AbstractSnmpValue so that ISO-8859-1 strings are accepted as "displayable".
Fixes bug NMS-5281. Also changed the handling of 63-bit hexstring counters in the
FCMGMT-MIB so that we don't accidentally try to handle 8-digit decimal values as
weird FCMGMT counters. Fixes bug NMS-6202.
Merge branch 'master' of https://github.com/OpenNMS/opennms