Plotting to bitmaps

There are a few reasons we want to plot to bitmaps:

1. Plotting to thumbnails (which we do already).
2. Plotting Canvas elements.
3. Optimising tiled SVGTiny rendering by pre-rendering SVG to bitmap.

So the plan is:

1. Make NetSurf core depend on libnsfb for its memory backend.
2. Rip the plotter implementation out of the NetSurf framebuffer
front end, and make it a core plot_bitmap plotter interface.
The core can use this, and front ends can choose to use it too.
3. Adjust the rendering pathways so they can take a bitmap to plot
into.

We might consider putting these features behind compile time options.

--
Michael Drake http://www.netsurf-browser.org/