Fog Volume 2 improvements

I wanted to learn about volumetric rendering (raymarching) for long time but never had the chance until now.
A client asked me to make a cloud effect, so I have spent some time learning about this topic while improving Fog Volume.
First thing that Fog Volume was missing was the intersection with scene objects, which is solved now. A better accumulation method has been also implemented as well as a rough method for lighting (subject to change in future updates).