Update stats structure (remove separate loss structure)
Better checks for drops
Fix email in copyright
Move default secret to radsniff.h
Freeing the filter tree should be one of the last things we do...
Support decoding IPv6 headers

Fixes decode errors when IPv6 loopback address is used, and allows radsniff to be used to decode RADIUS over IPv6.
Set start_pcap outside of the processing loop
Batch up packet processing
Update help text