Generalize the "Barnsley Fern" fractal

The Barnsley fern fractal is great - let's make it better. Some ideas:

• Blurred pixels: for each "linear map", add the option to sample the region near the resulting point, rather than right on top of it. This would enable, for example, the stem of the fern in the barnsley fern to be wider and with a somewhat smoother edge, rather than a single pixel.
• Arbitrary Maps: the barnsley fern hard-codes four linear maps... but there are other versions of the fractal with more (or less). Examples might be the "leaf" or "dragon" fractals by Paul Bourke.
• Color by map: for each of the maps, add the RGB color to the map, rather than at the fractal level. This would enable different features of the fractal to be colored differently. For example, making the stem of the fern a darker shade than the leaves.