Ranges of filter parameters

[jamshark70]

I wouldn't mind to open a PR to document some of the expected parameter ranges, but I thought I'd ask first:

• VAxxx filter resonance is 0.0 - 1.0?
• VAxxx filter drive is 0.0 - 1.0?

I haven't checked other help files yet -- I think I'm guessing right, but the helpfiles don't really confirm it. Once confirmed, I'd be happy to add the ranges to the help files.

[madskjeldgaard]

I think you are correct about this @jamshark70 - feel free to make a PR. And thanks a lot!