This changes drastically the implementation to leverage arbitrary writes
in order to reduce complexity, memory usage and increase speed.
Since we are no longer dependent on the framebuffer requirement, we can
allocate bigger size texture that fits all views and avoid the extra.
Transparency, holdout and emissions are no longer deferred and are now
composited using dual source blending.
The indirect lighting and raytracing is still not functional but will
also gets a large refactor on its own
This allows removing the indirection for lods during shading since the
tile is not owner of the page unless it uses it.
The cache system is quite more complex but makes it easier to spot
errors since the pages are not scattered into the tile texture.
This also simplify allocation since the free heap is separated from the
cache.
