v0.7.7

Add talkback and "turn on rta when select channel function".
Both of the can turn on in appsettings.json.

Talkback function:
-define a channel number in the settings. After that when the scrub button is pressed that channel is unmuted, when the button is released the channel is muted.

The rta function is turned on a channel when the select buttons is pressed on the controller (if RtaOnWhenSelect is true in the settings)