A integrator UGen with controllable attack and release times. While Decay has
a very sharp attack and can produce clicks, Decay2 rounds off the attack by
subtracting one Decay from another. It can be seen as equivalent to
Decay.ar(in, release) - Decay.ar(in, attack)
Note: This should not be confused with LagUD which does not overshoot due to
integration, but asymptotically follows the input signal.
input signal to be processed