Plane helpers and a new plane options ioctl

Here are the utility functions again. Rebased and updated slightly. I adapted drm_framebuffer_check() to handle multiple handles, and I changed some of the error values it returns. The plane options ioctl is a bit of an open question. I started by adding separate ioctls for some subsets of the fu

Plane helpers and a new plane options ioctl

Here are the utility functions again. Rebased and updated slightly. I adapted drm_framebuffer_check() to handle multiple handles, and I changed some of the error values it returns. The plane options ioctl is a bit of an open question. I started by adding separate ioctls for some subsets of the fu