torcontrol improvements and fixes

- Force AUTHCOOKIE size to be 32 bytes: This provides protection against
  an attack where a process pretends to be Tor and uses the cookie
  authentication method to nab arbitrary files such as the
  wallet
- torcontrol logging
- fix cookie auth
- add HASHEDPASSWORD auth, fix fd leak when fwrite() fails
- better error reporting when cookie file is not ok
- better init/shutdown flow
- stop advertizing service when disconnected from tor control port
- COOKIE->SAFECOOKIE auth

src/torcontrol.h

@@ -14,6 +14,7 @@ extern const std::string DEFAULT_TOR_CONTROL;
 static const bool DEFAULT_LISTEN_ONION = true;
 
 void StartTorControl(boost::thread_group& threadGroup, CScheduler& scheduler);
+void InterruptTorControl();
 void StopTorControl();
 
 #endif /* BITCOIN_TORCONTROL_H */