Cycles Denoising: Enable floating point exceptions in filter code if enabled in CMake

Cycles Denoising: Add missing util header file to CMake

Cycles Denoising: Fix wrong argument order that caused massive overblurring

Merge remote-tracking branch 'origin/master' into soc-2016-cycles_denoising

Conflicts:
source/blender/blenloader/intern/writefile.c

Cycles Denoising: Use device-independent denoising code for CUDA as well

As a result, cross-denoising on CUDA works now.

Cycles Denoising: Use device-independent denoising in the CPUDevice

Cycles Denoising: Implement device-independent denoising algorithm to deduplicate device code

Instead of implementing the full algorithm inside the device, the new code just calls the device in order to run specific kernels while handling all the high-level logic outside of the individual devices.

Merge remote-tracking branch 'origin/master' into soc-2016-cycles_denoising

Cycles Denoising: Move denoising kernels to a separate compilation unit

Previously, the denoising kernels were just included with the other kernels.
However, that is not ideal, since the kernels already take very long to compile. Also, it isn't needed since the rendering and denoising kernels share basically no code.

So, this commit adds intern/cycles/filter/, which contains the filtering kernels.

Cycles Denoising: Support GPU denoising from the command line

Cycles Denoising: Fix command-line denoising and add filter weighting adjust option

Cycles Denoising: Fix building without filter debugging

Merge remote-tracking branch 'origin/master' into soc-2016-cycles_denoising

Cycles Denoising: Change order of passes in the denoising buffer

Cycles Denoising: Remove useless functions

Cycles Denoising: Fix sample scaling for cross-denoising passes

Cycles Denoising: Fix multilayer handling when denoising after rendering

Cycles Denoising: Allow to ignore cross-denoising passes

Cycles Denoising: Implement new cross-denoising mode on CPU

Not very useful yet.

Cycles Denoising: Fix Whitespace errors