Change minimum required CMake version to 3.13
Update gtest version to v1.14.0
Change default sustain value in adsr to 1.0
Fix compiler warnings

drums:
Add choke functionality to bd, clap and sd
Add 'swoosh' filter to cymbal
Fix snappy bug in sd

polyfilur:
Velocity curve to filter velocity
Add support for LFO restart in oscillator LFO
Change default values in filter

ep:
Add support for sustain pedal, sostenuto pedal, soft pedal and all notes off
Add support for tuning pickup volume, timbre and gain per key
Change clang frequency and attenuation