Prevent MOD column to output on MOD CV

[yrn1]

With the new mapping feature, it would be nice if the MOD column in a modular track could be uncoupled from the MOD CV output. This way, the MOD CV output could be used e.g. as envelope output and the MOD column could then be used to modify some parameter of this envelope (or any other parameter) without affecting its MOD CV output.

This can currently somewhat be done with FX, but the MOD column itself becomes useless as soon as the MOD CV output of its track is used for something else.