Woovebox compressor implementation

The Woovebox compressors/limiters use a mechanism loosely based on the way an analog capacitor or tube works, rather than being a millisecond on/off affair. This gives the Woovebox compressor a slightly smoother, more analog sound/behavior.

Low attack (or decay) values charge (or discharge) the virtual capacitor faster. Whether the capacitor charges or discharges is determined by whether the incoming amplitude is higher or lower than the threshold. The capacitor's virtual state of "charge" is used as measure of how strong the compressor/limiter should crunch the signal. If the capacitor is fed long enough (e.g. signal is above threshold for long enough), the compressor/limiter's ratio should approach the specified/desired ratio. If the capacitor is no longer fed (e.g. signal is below threshold), the "charge" starts dropping off and the compressor/limiter's ratio should approach 1:1 again.