Probe for SOCKS port 9050 before using 'auto'
In the context of legacy/trac#7182 (closed), another extremely confusing issue is that on Windows, TBB will open a Tor listener on 9050 first and if it can't, it will open a random port. I propose that all TBB releases follow this convention - open 9050 or a random port. This in theory will allow people to just install TBB if they need Tor Browser and if they want to use Tor generally, they will get it without any fuss as long as they start any Tor related software (eg: Vidalia bundle, TBB, system Tor + TBB, etc).