Adding an @abs attribute to bufscale

[rconstanzo]

Popping this in here as a feature request as I can imagine it being useful across all environments.

Based on discussion in this thread on the discourse about looking for zero-crossings in a buffer, it would be great to have an @abs attribute in fluid.bufscale~ where the values are rectified before being scaled.

This would making looking for zero crossings very easy, as well as being able to do more meaningful peak picking/stats on bipolar (audio) signals.

The alternative ends up being quite clunky (in Max at least) as you have to manually uzi, abs and then query the values you want.

[jamesb93]

To be honest, this seems really niche and feature bloaty. Not sure how to best meet the feature request in another way though, beyond rectifying it using another bufscale step beforehand.

[rconstanzo]

I can see that, particularly since there aren't too many transformation types available (beyond purely scaling min/max and clipping).