Creates and returns a radial gradient. Parameters (cx, cy) specify the center, inr and outr specify
the inner and outer radius of the gradient, icol specifies the start color and ocol the end color.
The gradient is transformed by the current transform when it is passed to fillPaint or strokePaint.
NVGPaintradialGradient(NVGContext ctx, float cx, float cy, float inr, float outr, Color icol, Color ocol)
Creates and returns a radial gradient. Parameters (cx, cy) specify the center, inr and outr specify the inner and outer radius of the gradient, icol specifies the start color and ocol the end color. The gradient is transformed by the current transform when it is passed to fillPaint or strokePaint.