Remote Frame Buffer

I've taken a few days off trying to get NetSurf to work in order to add basic Remote Frame Buffer protocol support to the Wimp.

That's the protocol used by VNC, so now the Wimp can be used from a VNC client, either with or without displaying to an actual display. (Keyboard support is not yet included, but the mouse works.)

To use it, set the environment variable ROLF_VNC to anything (at the moment, later it will be used to define the port to listen at and, possibly, the frame buffer resolution). If ROLF_VNC is not defined, or FRAME_BUFFER is, the proper frame buffer device will be used (rather than a shared memory bitmap).

In use, it's much faster than running the system under qemu, and I can use the host system to debug code. I'll now go back to working out the coordinate system for netsurf.