- Cursor is not necessary anymore as rendering hardware vs software
cursors just depends on "where" you render the cursor.
- Format is replaced by drm-fourcc and more related to buffers and
therefor the allocator module anyway.
- GL/Glium are replaced by the renderer module.
- Software was unused and very small anyway and can be implemented
with the new renderer api.
- SwapBuffersError is (for now) just moved into the top-level backend module.
- new backend rendering via egl via gbm directly on a drm device
- refine EGLContext and EGLSurface dependencies through lifetimes
- fixup the old winit backend to work with these changes
- add new example using the drm backend instead
- change GliumDrawer to be static for the drm example
- Make id be an `u64` to be able to populate it by a hash
- Add internal interface to get a mutable capabilities reference from a `Seat`.
- `InputConfig` type does not need to be `Sized` on `InputBackend`