This commit significantly improves the usability of the volume controls
for controlling volume in a way that matches intuitively onto human
needs and loudness perception.
Using the third power of the volume is a good approximation of the
quasi-logarithmic psychoacoustic system, while being defined everywhere
and preserving the useful quality of 0% volume mapping onto gain 0.0.
The use of this exact mapping function is a prior art established by
e.g. PulseAudio, among many other programs.
Fixes#24488
Niklas Haas
6096116526