ReaFIR interface improvements

ReaFIR is great as an eq plugin but it can be quite tricky to set up the curve. I have a few suggestions which I think would make it much easier and make the plugin more useful.

1. Zoom! Trying to add/manipulate points in the low freq range is difficult. If we could zoom horizontally then it would be much better. Vertical zoom would be nice too but horizontal is essential.

2. Better curve editing. If we could manipulate the curve in the same way that we can manipulate REAPER envelopes it would be just awesome. Having multiple selection and all the different curve types would be fantastic.

3. It would be ace if we could bypass individual points on the curve, allowing A/B comparisons on a finer scale. If this were combined with multiple selection it would be just amazing.