setNightMode

Turns the night mode on or off (#442): the quiet parts of the sound are brought up and the loud parts down, so speech can be followed at a volume that does not wake the house, as a receiver's night mode or mpv's dynaudnorm does. It acts on the output after the downmix, with a gentle attack and release, and never passes full scale. Off, the default, costs nothing and leaves every sample as it was. A change glides in and out, so it never clicks, and is heard once the audio already buffered has played, as a setBalance change is. Published as PlayerSnapshot.nightMode.