Ability to create multiple accessories for each Zone on the Yamaha Receiver.

[tomun]

This change allows the plug-in to create multiple accessories for each of the speaker zones on the receiver.

The zones must be specified in a new 'zones_as_accessories' key in the config. I renamed the 'SetMainInputTo' key to 'set_input_to' as it can now apply to multiple zones, however the old key name is backward compatible.