[FEATURE] Add 'shapeburst' fill style. Shapeburst fills implement a buffered gradient fill, where a gradient is drawn from the boundary of a polygon towards the polygon's centre. Configurable parameters include distance from the boundary to shade, use of color ramps or simple two color gradients, optional blurring of the fill and offsets.
More descriptive name for colour parameters in gradient and shapeburst fill data defined symbology dialog
Avoid multiple creation and destruction of arrays during calculation of distance transform in shapeburst fills
Add a slider for setting the shapeburst fill blur amount
Consider rasterScaleFactor during shapeburst fills
Limit resolution of symbol fills during composer previews to improve composer responsiveness