Add gradient range rendering

[Destroy666x]

A mix of range and gradient would be great. So basically instead of having constant colors until some tresholds, it'd be nice if the thresholds were middle points of gradients instead.

[phandasm]

So a 4-color gradient? I feel like 3 is enough, if anything I'd add a tricolor mode with adjustable midpoint that works like the existing gradient mode. Range mode is basically meant for level meters.

[Destroy666x]

Ye, the main suggestion here is adjustability of where the gradient changes colors vertically, like in range.