SCOPE Buffer size too small

[katef]

Hiya! I've been playing with using the scope in XY mode to display text, and I'm hitting against what I think is the hardcoded BUFFER_SIZE limit here:
https://github.com/VCVRack/Fundamental/blob/v2/src/Scope.cpp#L5

Here's about as much detail as I'm able to show before it breaks down:

(this is supposed to be a 5x5 grid of the letter "A", but most of them aren't being drawn)

after this, if I turn up the resolution for my inputs, the scope sort of mysteriously gives up and shows simplified waveforms (the ones in my images are already being cut down I think).

or here, I was trying to render high-frequency blocks for each pixel in the grid, where the lissajous patterns are, to make a sort of solid block. But I was only able to get the density you see here, before the scope gave up:

I think both of these are due to the buffer size.

I'd make a PR to bump this to 1024 or so, but CONTRIBUTING.md says not to, and I'm sure you'd want to check that whatever larger value is fine for performance and such.

Thank you!