Feature: Equalizer for sound in-/output

[sjjh]

Idea: The framework demo application contains a demo equalizer. I belive it would be great to have an equalizer reacting to real sound. I can imagine:

• input via microphone (selected system mic)
• output via selected system output device

Not sure if two independent widgets or one with a config option would be better. I believe it is easier to just grep the system default device, than let the user select a device manually specifically for the led matrix, but maybe there is a user case for that a s well. If two led modules are attached, we can think about stereo sound as well. :D