PIM: add some v2 test cases

The sample captures come from packetlife.net through courtesy of Jeremy
Stretch.
NFS: use tok2str()
NDOize the rest of util.c
SMB: make use of tok2str() and ternary conditional
put Hannes' prior captures to work

Add test cases for the .pcap files added in 2005 (complements commits
279c3bd, 80d7284 and 0dcd9ac).
use more PacketLife captures for test cases

Improve coverage for ISAKMP, IGMP and HDLC. Add initial coverage for STP
variants, DECnet, RADIUS, DTP, LACP, LLDP, CDP, VTP and UDLD.
NFS: prepend %x format with 0x (mitigates GH #35)