[mythtv] update cec support to work with v2 of libcec

[mythtv at phipps-hutton.freeserve.co.uk]

Quoting Raymond Wagner <raymond at wagnerrp.com>:
> There's little reason to even enable CEC at the moment, as the only  
> thing MythTV allows at current is to send a power toggle to the  
> first TV it finds on the bus. I'm intending to set up some form of  
> graphical mapping through the frontend Services API to allow easier  
> definition of devices and behaviors, but have no idea when I might  
> get around to that.

It's nice that you can use the TV remote buttons to operate  
mythfrontend too but I think having the frontend control what is  
essentially an input device is wrong.  
https://github.com/bramp/libcec-daemon is a better approach, all  
programmes will get the TV remote keys not just the frontend, it would  
be easy to add a socket to send CEC messages so you can do whatever  
you want to the system from scripts run from myth events. I guess  
eventually it will end up as a kernel driver with mapping similar to  
ir-keytable.

Cheers,
Tim.