Lircd compatible listening mode

[bengtmartensson]

The Lircd socket command interface should be supported. In the multithreaded setup (#1) just listen to socket 8765 (or alternative), and run it in a thread.

• SEND_CCF_ONCE should also be supported.
• Support for named pipe operation (/var/run/lirc/lircd etc) is not crucial, "nice-to-have".
• This is not to be combined with Lirc socket broadcast messages (cf. Listener mode and Lirc socket broadcast #3).