Blender Git Loki

As suggested by Campbell, rather use BVHTree to get len_diff in this morning's fix.

Note than it's using nearest faces, since it showed to be much more performant than
nearest vertex (quite odd, it's about 40% slower for the first element, then 50 times quicker
for all others, as if BVH was cached, and building face was slower than verts one,
but then using it, much quicker!).

CMake: add glew-mx library

CMake: use our template for finding the glew library

Fix bundling of requests on debian-like systems

Couple of issues:

- Debian systems doesn't use site-packages but uses
dist-packages instead.

- Requetss from ubuntu repository depends on urlllib3
and chardet, which also implies six. copy those libs
as well.

I know it's all rather annoying, but no that much
choise is in here..

Switch buildbot to new llvm/oiio/osl

Make requests python package to be detected in the same way as numpy

This solves missing requests package reported on the systems where it's
located in dist-packages rather than in site-packages.

To do this there's now a helper macros which handles both requests and
numpy now and could be used for more packages in the future.

Reviewers: campbellbarton

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D686

Fix T41191: Face snapping doesn't work properly.

Issue was caused by rB47ec0394ca3d, which disabled BBox check in editmode - but bbox check was also
setting `len_diff`, which is mandatory when doing ray_start_local correction for ortho view...

Now, in this case, we do a quick rough compute of len_diff from vertices coordinates (accuracy is not
needed here, we just have to be sure corrected `ray_start_local` remains 'before' (outside) of the
geometry).

Fix T41206: Render Border - Operator Panel - Only Camera - Broken?

This is rather internal use only, no need to expose this option to
the redo panel.

Fix T41201: Blender Crashes when UV Editing

Disable adding snapping point outside of 3D space for now,
visualization of the points is not implemented outside of
this space and silently adding them wouldn't really be a
good idea.

Warnings

Reduce OM limit for sculpting after discussion with Antony

That's rather tricky to think of a good threshold here, and
maybe we'd better use something based on the number of faces
instead.

Anyway, let's give it a try this way and see what happens.

Fix T41221: 3d view rendered mode crashes on new scene

Fix T40831: Shrink wrap modifier causes very high CPU usage when targeting meshes with shaped keys

Same issue as revious one -- need to start OMP threads only
when there's enough data to crunch.

RNA: check for valid ranges with int properties (C11 only)

Fix T41193: 2.71 use 100% of CPU at sculpt

Issue wascaused by the famous OpenMP crap in MSVC2013,
so only way is to use openmp threading if number of BVH
nodes is high enough.

Made it 8 for now, which seems to work rather fine on my
laptop and adult dragon from sintel. But maybe it's to be
adjusted a bit more.

Fix invalid RNA limits

UI: Change appearance for panel drag area (D637)

Patch by blakenator with own edits

Fix T41139: Cycles Hair BSDF roughness problem

T41196: Python call of bake operator cause Blender Crash

We could make the exec to also show the progress bar, but I think it is not needed.

ignore in-source doc building dirs