* Bugfix, rasterization was shifted half a pixel.
* Remove scaling of bias by render size, there is something to be
said for doing to compensate for lower shadow buffer xy resolution,
however the z-resolution does not change and this seems to have a
larger effect.
* Remove clamping of filter size by soft factor. Now it is clamped to
1 pixel instead to ensure there is some AA. Why this was done this
way is not clear to me, however on decreasing shadow buffer resolution
this would change the softness by increasing the filter size.
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