Provide feedback mechanism for clock-skew and other bad problems

TBB 3.0 currently has a button to copy Tor logs to the clipboard. It's good enough to enable support by knowledgeable people, but it is also good to enable at least a minimal level of self-support.

One misconfiguration that can prevent Tor from working is clock-skew. Vidalia made a bright red message out of it. Having some feedback mechanism in TBB 3.0 for similar critical issues would be good.