Blender 2.78b: Point addons to an updated revision

Blender release: We are officially 'b' now

[msvc] cmake fixes to support the recent for oiio/ffmpeg/numpy version changes.

Fix fluid sim build error with MSVC.

Fluids: improve multithreaded CPU usage.

Fixes for clamp-omp, fewer shared variables, fix some cases of threads writing
to the same memory location. Issue found by Jens Verwiebe, who reports 30%
speedup with 16 core CPU, when using this with a recent clang-omp version.

Cycles tests: Allow python auto-exec

Cycles: Fix rng_state initialization when using resumable rendering

Fix compilation error with latest OIIO 1.7.8

There are some changes in OIIO includes so now need to do some
things differently.

Return correct alpha for environment map in GLSL

Fix T49405: Crash when baking with adaptive subdivision

Blenders baking system currently doesn't support the topology used by
adaptive subdivision and primitive ids will be wrong or out of range
leading to crashes. Updating the baking system to support other
topologies would be a bit involved, so for now we simply disable
subdivision while baking to avoid crashes.

Cycles: Don't rely on indirectly included algorithm

Cycles: Fix typo in the panel name

No user visible changes, it was a typo in the name of the class.

Spotted by povmaniac in IRC, thanks!

Cycles: Update current Cycles version

Fix T50491: Cycles UI breaks when pushing F8.

Cycles add-on did not actually support reloading correctly.

When you want to correctly reload sub-modules (i.e. modules of an add-on
which is a package), you need to use importlib, a mere import will do
nothing with already loaded modules (RNA classes are sort of
pre-registered when they are evaluated, through the meta-class system).

Cycles: Use more const qualifiers to avoid possible issues

Cycles: Cleanup, split one gigantic function into two smaller ones

Cycles: Store time in BVH nodes

This way we can stop traversing BVH node early on.

Gives about 2-2.5x times render time improvement with 3 BVH steps.
Hopefully this gives no measurable performance loss for scenes with
single BVH step.

Traversal is currently only implemented for QBVH, meaning old CPUs
and GPU do not benefit from this change.

Cycles: Add option to split triangle motion primitives by time steps

Similar to the previous commit, the statistics goes as:

BVH Steps Render time (sec) Memory usage (MB)
0 46 260
1 27 373
2 18 598
3 15 826

Scene used for the tests is the agent's body from one of the barber
shop scenes (no textures or anything, just a diffuse material).

Once again this is limited to regular (non-spatial split) BVH,
Support of spatial split to this feature will come later.

Cycles: Add option to split curve motion primitives by time steps

The idea is to create several smaller BVH nodes for each of the motion
curve primitives. This acts as a forced spatial split for the single
primitive.

This gives up render time speedup of motion blurred hair in the cost
of extra memory usage. The numbers goes as:

BVH Steps Render time (sec) Memory usage (MB)
0 258 191
1 123 278
2 69 453
3 43 627

Scene used for the tests is the agent's hair from one of the barber
shop scenes.

Currently it's only limited to scenes without spatial split enabled,
since the spatial split builder requires some changes to work properly
with motion steps coordinates.

Cycles: Add utility function to calculate curve boundbox from given 4 keys

Also fixed some issues with motion keys calculation:

- Clamp lower and upper limits of curves so we can safely call those
functions for the very first and very last curve segment.
- Fixed wrong indexing for the curve radius array.
- Fixed wrong motion attribute offset calculation.