Add some form of error logging/reporting

[jwalthour]

Right now all exceptions that are caught are silent failures. Would be better to have some sort of logging or crash reporting feature.

maybe a copyable text box with the stack trace just before exiting? That'd be the simplest.

Another option would be a text file that's cleared upon startup and written with debug/info/warning/error lines.

If we do the text log, it should include these items (handled silently right now, or not at all):

• Problems initializing an interface
• Problems in a packet listener thread
• Problems in host filtering thread
• Problems loading a manufacturer icon
• Problems loading any of our lookup files
  • MA-L/OUI
  • Icon index
  • Bookmarks/nicknames file

[jwalthour]

Could also write a method in MainWindow that the other items call via an event