Provide a --debug flag

[phihag]

We should include a --debug flag that determines and prints additional information for bug reports. The report should include:

• IPv4 and IPv6 address
• Proxy settings
• youtube-dl version
• Python version and implementation
• OS version and architecture
• Whether lxml is available or not

[FiloSottile]

Actually, --version ATM is more --debug (still incomplete...)

[jaimeMF]

Do you think switching to Python's built-in module logging is a good idea?
It would make easier to log debug messages anywhere in the code.

[phihag]

The idea I had here is to retrieve better error reports, so this would only affect on startup. I'm unsure about the logging module, since that's - at least in my experience - where traces go to die. I'd rather have messages as one stream of messages with types so external applications can easily consume them.

[jaimeMF]

Ok, but logging makes easy to turn on the debug messages, you can log to file-like objects (http://docs.python.org/2.6/library/logging.html#stream-handler) or customize the messages template.

[kenorb]

+1

[ocisly]

@phihag Can this be closed now that there is a --verbose flag or is this different?

[phihag]

@codesparkle Yes, although it may be a good idea to add a further flag to output IP addresses, since we can detect LAN/ISP/national censorship (which often causes users to file issues) that way.