VISH amplitude scaling

[BlamesJake]

Clampling in VISH usually confronts the ability to build up the amplitude's energy due to consecutive envelopes (ie: short attack/long realease values get clamped pretty easily, specially with "times x10" engaged).

The request is to add a pre-clamped scaling option so we can have a wider range of that effect before it clips. Could be placed at right-click menu with fixed scale downs (x.75, x.5, x.25).

A non-clamped option also could be implemented. This way we can handle the amplitude scaling continuously via an external VCAs and avoid the clipped "hold" stage.