[PD] datastructures midirecorder

[João Pais]

> Hello Rob,
>
>  scalars can't be deleted actually without the GUI, but there are several tricks for doing something like it.
>
> One is about using float indexes instead of using pointer order, and then set to -1 or another value that doesn't count

you can also make "inactive" scalars invisible, then they're not seen. and though some export+import, filter these scalars out in the process.