- Add "muted" class for styling the muted state.
- Add "zero-on-mute" boolean option to control slider position
when muted.
- Add "unmute-on-volume-change" boolean option to control whether
to automatically unmute when the volume changes.
This Patch allows the stretching of modules-{left,center,right} as well
add a "expand" flag to AModule. This allows one module to consume the
leftover space.
To allow the left or right modules to fully consume the center, the
changes also include a way to remove the center box (center_)
altogether.