Add IsolateDestPort and IsolateDestAddr support

* Adds support for IsolateDestPort and IsolateDestAddr, which is useful for chat applications
* Adds support for sending SIGNALs and for getting configuration status from control port
* Adds tests for SOCKS isolation and HUP signal
* Minor code cleanup

One thing I noticed is that it's impossible to run two connection tests because there's no way to completely shut down Tor without it exiting the test. Lots of banging my head on the table trying to figure that one out.