interim support for CV-MIDI and CV-OSC

provide an interim solution for sending CV output from rack to external MIDI or OSC devices/apps with support for as much of the MIDI protocol as possible, and of course everything OSC. MPE support too?!

```
rackcli --cv --channel CHANNEL [--map-midi mymidimap.json | --map-osc myoscmap.json] --name NAME
rackcli --cv --stop [--channel CHANNEL | --name NAME]
```