Feature: dump current state to logfile

Sometimes when troubleshooting a network issue, it might be useful to log all the information the tool currently has in a log file for parsing and perhaps a more thorough look than can fit in the UI.

Note that this should work both for when paused and not paused.

A good key binding might be "d", but other ideas are welcome as well.

The format for dumping to a file should be the same one we use for "raw_mode".