use 'filesystem' class hierarchy for protocol traces
When using SIMtrace2 for passive sniffing, we currently only have very minimal decoding in wireshark.
It would be rather useful to make use of all the information we now have in the pySim 'filesystem' class hierarchy for protocol trace analysis
- input could be GSMTAP (live socket or pcap file open)
- we can passively trace the position in the filesystem hirarchy and know which path/file is selected
- we can print symbolic names of the files as they are selected
- we can decode the binary/record data as it is read or written
- we can decode the status words