Output routing modes

[Andreya-Autumn]

Presently, each channel in the mixer can choose where it should send to. This is redundant and unnecessarily fiddly in many cases (but apparently common in samplers), so let's add a couple modes which will be friendlier in many common cases:

Note: "Output" == "VST out stereo pair (1-indexed)" throughout.

• "Summing" mode. All mixer channels send to main. Main sends to VST output 1. Auxes also send to main by default, but could perhaps optionally send to the next 4 outputs (in order, not selectable), or both.
• "Inline" mode. All mixer channels send to their corresponding-numbered output directly. Chan1 -> Out1, Chan2 -> Out2, etc. Perhaps the main channel could still get a sum also, but if so it should move to the last output to get the intuitive numbering above.
• "Free Routing" mode, or something. What we have now.

[Andreya-Autumn]

UI-wise, I imagine that the output select dropdown just becomes a label that shows the destination in the first two modes. So you always see where stuff goes.

Except auxes in sum mode of course, if we give them options there. In which case the first aux would get a menu saying "Main, Output 2, Both". The next aux would get output 3, etc.