Connect to a SerialForwarder with Python

In the current implementation the Python tool tos-deluge has an exclusive connection to the programming device. For a project I added support for the Java SerialForwarder application.

The focus was to support connections to the SerialForwarder, not to break the other connection methods, and to keep the new classes compatible to the existing ones, i.e. the class SFClient takes the same arguments as the AM class but doesn't implement blocking behaviour, or sequence numbers.

I don't expect this to be merged, but maybe it can serve as a starting point for a SerialForwarder support with Python.