Fix T40925: Scene gravity hard limited

Remove hard limit, but keep soft limit because it might cause some
negative effect on physics stability.
Correction to recent rip-tear
Fix UI still allowing addition of slots in cycles if material did not
use nodes.
Implement option to parent object to undistorted position of 2D track
Buildbot: Never write 'master' branch in packed file names.
Cycles: Updates for new OSL 1.5 API.

Differential Revision: https://developer.blender.org/D662

Patch by Sergey and myself.
CMake: use a list for PLATFORM_LINKLIBS
Source Checkers: Include intern/ libs we maintain in spelling checks
Fix atomix operations on unofficial 64bit archs
OSX: adaptions needed for renewed osl/oiio/llvm
One more fix for new OSL libs.
Cycles: Drop old OSL closure compatibility code.

This was added to keep custom OSL scripts with Toon and SSS closure calls working. 1 year after the change, we can drop the compatibility code now.
Yet another OSL compilation fix...sorry.
Fix inconsistent use of print_error() and fprintf(stderr, ...) in MEM_guarded_printmemlist_internal().

Also extended the size of buf[] in print_error() to prevent mem_printmemlist_pydict_script[]
from getting truncated when MEM_printmemlist_pydict() is used.

Differential revision: https://developer.blender.org/D675

Reviewed by: Campbell Barton
Install_deps: Update OSL to 1.5.10, llvm to 3.4 and oiio to 1.4.11.

Note: had to swicth back to own repo for osl as well, ILM guys seem unable to handle
CMake build system properly!
Install_deps: Force to always compile OCIO for now.

This is a much simpler fix to that libyaml-cpp mess, since doing it that way we get our static own
libyaml-cpp... And this should work for all platforms (realized libymal-cpp-ver option was only
implemented for deb-like distro, since it was the first place where issue showed up :/ ).
Switch to Cuda 4.0 style api for kernel invocation. This is a small clean-up that has no functional changes but makes code a bit more readable.

Differential revision: https://developer.blender.org/D659

Reviewed by: Sergey Sharybin, Thomas Dinges
Minor changes:

* Changing UV map updates the UV editor.
* UV Layer -> UV Map
Cycles Bake: show progress bar during bake

Baking progress preview is not possible, in parts due to the way the API
was designed. But at least you get to see the progress bar while baking.

Reviewers: sergey

Differential Revision: https://developer.blender.org/D656
Fix bug in validate mesh code (could use index out of range).