Redo the autowah effect
Redo the autowah effect

It's now a low-pass filter with a cutoff that varies according to the input
signal amplitude.

There remains issues with apparent feedback in the resonant frequency with high
resonance values. The actual cutoff range for the filter is also a guess.

alexxvk/openal-soft,irungentoo/openal-soft-tox,Wemersive/openal-soft,aaronmjacobs/openal-soft,franklixuefei/openal-soft,arkana-fts/openal-soft,irungentoo/openal-soft-tox,BeamNG/openal-soft,mmozeiko/OpenAL-Soft,Wemersive/openal-soft,BeamNG/openal-soft,mmozeiko/OpenAL-Soft,franklixuefei/openal-soft,alexxvk/openal-soft,aaronmjacobs/openal-soft,arkana-fts/openal-soft