Merge branch 'master' into gsoc-2018-many-light-sampling

Cycles: light_tree_pdf() now accounts for splitting

Cycles: Removed unused code

Cycles: Removed energy term in SAOH denominator

Cycles: Added more comments and renamed variables

Cycles: Light tree: volume and MIS fixes

Cycles: Light tree split heuristic fix

Cycles: Picking position and normal fix for MIS

Cycles: Light tree: Area light fix

Cycles: Light tree: energy and light picking fixes

Cycles: Light tree instancing and energy fixes

Cycles: WIP: Volumes are not using the light tree.

Cycles: Light tree optimization

Cycles: Light tree related bug fixes

Cycles: Several emitters per leaf in light tree

Cycles: Bug fixes

Cycles: Updated SAOH with regularization factor

Cycles: Updated cone aggregation and measure

Cycles: Updated the importance metric

Cycles: Updated rescaling of random numbers

Cycles: Updated the split heuristic

Cycles: First iteration on split traversal

Merge branch 'master' into gsoc-2018-many-light-sampling

Fix: Merge conflict with background resolution

Cycles: Background lights works with light tree

Cycles: Support for distant lights

Cleanup: Replaced space tabs with real tabs

Cycles: New design for PDF computations

Cleanup: Refactored code

Cycles: Area lights support and better energy estimation

Merge branch 'master' into gsoc-2018-many-light-sampling

Cycles: Added a checkbox in Blender's GUI to turn on/off the new light sampling…

Cycles: Implemented the SAOH splitting method

Fix: Minimal compilation error fix

Added simple construction and sampling code for light BVH

My own build path modifications

Fix OpenCL compilation error - BPT without SSS.

make.bat: fix support for building with just the build tools installed.

Fix missing movieclip ID type in allowed ones for Outliner...

Edit Mode: add success return value

DNA: add OB_DATA_SUPPORT_EDITMODE macro

Cleanup: Get rid of G.main in BKE_material.

make.bat : fix release build not getting the right settings.

make.bat : improve error message while detecting the msvc runtime when using…

make.bat : add support for building with ninja and clang together.

Windows: Add support for building with clang.

UI: center align number buttons w/o text

Fix Cycles + OSL build error, pass main to node editing functions.

Cleanup: Nuke most of remaining evil G.main from RNA.

Cycles: Fix problems in the IES loader when rendering with no file selected

UI: replace BLI_strncpy w/ memcpy

Recently added IES conflicts w/ EEVEE

3D View: minor change to NDOF view orbit

Fix restrict error in BLI_str_format_byte_unit

make.bat : Fix builtime.txt being written in the wrong folder.

Cycles: Add Support for IES files as textures for light strength

Threads: add spinlock hit for hyperthreading processors on Windows.

make.bat: Add support for building with ninja.

make.bat/cleanup: removed stray echo in make.bat

make.bat: refactor make.bat

Add number and memory size formatting throughout the UI

WM: check modal handlers for keymap lookups

[windows/make.bat] use a more reliable way of locating visual studio 2017.

UI: fix assert

3D View: add pixelsize function w/o UI scale

Cycles: Cleanup: Remove duplicated atan2f definition for OpenCL

Cycles Denoising: Don't use atomics in the accumulation kernel on CPUs

Cycles/Compositor: Add arctan2 operation to the Math node

3D View: remove poll 3D view for copy/paste

Fix T55034: Setting duplication group for multiple selected items only affects…

Fix Extend property of Lasso select tool in Mask editor not working

Fix T54336: Extend property of Lasso select tool in Node editor does not work

Fix T55137: Compilation failing on non-x86-64 architectures

Fix incorrect size in aligned lockfree realloc

Cleanup: strip trailing space from interface files

blenderplayer: add stubs

Fix T55093: Bisect + fill crash

Memory allocator: use lockfree calls internally

CMake: only include licences for enabled libs

Cleanup: use const for transform internal API

RNA: support for PARM_OUTPUT & PARM_RNAPTR

Fix too much memory usage for Cycles attribute map.

Fix/workaround RNA build error in C++ API.

Cleanup: correct variable names

WM: utility to find a keymap item from an operator