Fixed https://trac.torproject.org/projects/tor/ticket/11983 with the add...

...ition of some checks of incoherences in:

  * advanced:start_tor, tor:socks_port and tor:control_port
  * advanced:interface
I think that if we decide that the config file is incoherent from inside of settings we should raise an exception that is trapped by whoever calls it. Perhaps it's even ideal to not have the inconsistency check be done automatically at every read, but do it explicitly and handle exceptions there.