MIDI stream to exponential curve

In this patch the zmap object changes the scale of the incoming number stream from the ctlin object from the standard range of MIDI (0-127) – the 0 is bypassed so that it is translated properly once the range is mapped back to linear amplitude – to a specified range in decibels – in the case of the example from -63 to 0 dB. The dbtoa object then converts this back to linear amplitude which is used to control the amplitude of the cycle~ sending to the dac~ via the line~ and *~ objects.