[modules/pulseaudio] rate-limit pulseaudio events
[modules/pulseaudio] rate-limit pulseaudio events

attempting a different tack: Reduce the amount of draws that are being
emitted by the pulseaudio module to max. 2/s. That hopefully increases
reactivity and at the same time keeps flickering to a minimum.

see #917

tobi-wan-kenobi/bumblebee-status,tobi-wan-kenobi/bumblebee-status