Blender Git Loki

Eevee: Depth of field: Change final blending.

This new blending allows background to fill the gaps left by forground
objects. However this has a drawback, background objects that should be
partially occluded in this case can be seen through the blurred objects.

This does not fix the problem of blurred foreground over sharp background.

Also cleanup code to be simpler and remove unused geometry shader.