working implementation using NSConnection.

This is the final commit using the longtime deprecated NSConnection / PDO mechanism. This is only working when the functionalities of the Controller and Tracker are communicating between threads inside the same process. Inter-process communication is not possible with (P)DO anymore as the processes are sandboxed. So dedicated device drivers in user space are not possible without using a different IPC mechanism. Next development goal will be switching to NSXPCConnection and the XPC mechanism.