Increment version number to 3.0.20
Remove duplicate macros in libpacketdump

Ensure OSPF libpacketdump module won't segfault or print garbage
if a truncated OSPF header is passed into it.

Renamed 'len' field in OSPF header to 'ospf_len' to avoid
potential conflict with variables named len in libpacketdump
code.
Merge remote branch 'origin/develop' into develop