Control System: Control4

Changelog:

      - Added asynchronous feedback for volume and mute feedback

v318:

      - Added link to support web site

v317:

      - Add ability to specify RS-232 commands in hex format.

v316:

      - Add RS-232 pass-through command (in addition to the existing support for

       directly connecting RS-232 devices).

      - Add Control4 command for directly sending API commands.
      - Replace STA with "get ver inf" to get version to improve performance.