All the changes are mainly giving explicit tips on inlining functions,
so they match how inlining worked with previous toolkit.
This make kernel compiled by CUDA 8 render in average with same speed
as previous kernels. Some scenes are somewhat faster, some of them are
somewhat slower. But slowdown is within 1% so far.
On a positive side it allows us to enable newer generation cards on
buildbots (so GTX 10x0 will be officially supported soon).
Using camel case for variables is something what didn't came from our original
code, but rather from third party libraries. Let's avoid those as much as possible.
BVH traversal is not really that much a geometry and we've got
quite some traversals now. Makes sense to keep them separate in
the name of source structure clarity.
