Denonavr - sound mode ALL_ZONE_STEREO to sticky

Hi, thanks for all the work the denonavr module.

Using the sound modes: after ALL_ZONE_STEREO I can no longer switch to the other sound modes.

A Denon special feature: ALL_ZONE_STEREO must be off before any other sound mode can be selected. (A Just like in Harmony Hub, there needs to be a ALL_ZONE_STEREO_OFF option.)

Or, call ALL_ZONE_STEREO_OFF internally before setting the new sound mode.

A receiver OFF/ON always sets ALL_ZONE_STEREO off…

Thank you again !