color correct strips & preamp in audiovis based on base color value
Add command AudioVis to visualise playback audio spectrum

Implementation based on heliecho, w some changes & fixes. Still needs
tweaking, I'd say.
Base procedure color / brightness / etc off of last color
custom UDP protocol & offload FastLED to second core on ESP32

Had problems with a bit of lagging in rendering on the
ESP32_WS2801. Presumed it was bc of TCP resends etc, so switced to
UDP. It's really not important that we display every single frame, and
in exactly the right order. In particular, if a packet is lost or
smth, we would rather show a newer frame than have an old one resent.

Also, I've had trouble with single-wire strips like WS2813 on the
ESP32. Issue seems to be that it can't handle the relatively strict
timing requirements, compared to WS2801 where we send the clock signal
ourselves. Making use of the fact that Arduino for ESP32 is dualcore &
apparently runs FreeRTOS behind the scenes, we run FastLED.show() in a
separate task pinned to the second core. This seems to have solved the
issue perfectly for me.
web ui w color picker & esp32 works &
Add license
Clients connect to server & Client LEDs indiv. addressable by server
webserver + rgb ws2801 lighting works