User Interface: Add button color for indicating that the value differs from the interpolated one

One issue that especially newer users often run into is that they accidentally reset changes to the scene by switching frame without creating a keyframe first.

Therefore, this commit adds a new color that is used to draw properties if their current value differs from the one that would be set when switching to this frame.
This works both for existing keyframes as well as for currently interpolated frames.

Unfortunately the flags in but->flag are full, so I had to move the new flag to but->drawflag and pass that to all relevant functions.

I went with orange for the color since afaics it fits with the green and yellow that are currently used for keyframe states and since it's somewhat reddish to signify that there might be something to look out for here.

Reviewers: campbellbarton, #user_interface, brecht

Reviewed By: campbellbarton

Subscribers: brecht, predoe

Differential Revision: https://developer.blender.org/D3949

Cycles: Add sample-based runtime profiler that measures time spent in various parts of the CPU kernel

This commit adds a sample-based profiler that runs during CPU rendering and collects statistics on time spent in different parts of the kernel (ray intersection, shader evaluation etc.) as well as time spent per material and object.

The results are currently not exposed in the user interface or per Python yet, to see the stats on the console pass the "--cycles-print-stats" argument to Cycles (e.g. "./blender -- --cycles-print-stats").

Unfortunately, there is no clear way to extend this functionality to CUDA or OpenCL, so it is CPU-only for now.

Reviewers: brecht, sergey, swerner

Reviewed By: brecht, swerner

Differential Revision: https://developer.blender.org/D3892

Workbench: Add Curvature overlay for better visibility of surface detail for e.g. sculpting

The approach is fairly simple, just apply an edge detection filter to the view normal and scale the brightness based on that.

The overlay is disabled at object boundaries to avoid dark lines around objects.

Generally, this implementation follows the proposal of @monio at https://blender.community/c/rightclickselect/J9bbbc.
The changes are:
- Dynamic filter radius (on high-DPI displays, a radius of two is used)
- Options to reduce the strength of both ridges and valleys
- Tweaked function for the strength reduction (the original method actually had a local maximum, resulting in a brighter line inside valleys)
- Multiplication for blending instead of overlay, which doesn't work reliably with scene-referred intensities
- Renamed to point out the distinction between it and the SSAO-based cavity overlay

Reviewers: jbakker

Reviewed By: jbakker

Subscribers: billreynish, manitwo, linko, monio

Differential Revision: https://developer.blender.org/D3617

Render API: Support arbitrary length for custom image metadata fields

Cycles: Write Cryptomatte metadata according to the specification

Reviewers: brecht, sergey, swerner

Subscribers: creamsurfer, Tanguy, Noss, SteffenD

Differential Revision: https://developer.blender.org/D3862

Cycles: Support generating Denoising passes without actually denoising

Needed for the animation denoiser since the denoising filter is done separately there.

Reviewers: brecht, sergey

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D3833

Cycles: Expose noisy image pass by default when rendering with denoiser

Apparently quite a few users would like to have the noisy pass available when using the denoiser, and since it's being generated anyways we might as well expose it by default.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3608

Revert "Workbench: Add Curvature overlay for better visibility of surface detail for e.g. sculpting"

This reverts commit e9a60ce199200e25d2a6e9d722ad7e8de8cab206.

Workbench: Add Curvature overlay for better visibility of surface detail for e.g. sculpting

The approach is fairly simple, just apply an edge detection filter to the view normal and scale the brightness based on that.

The overlay is disabled at object boundaries to avoid dark lines around objects.

Generally, this implementation follows the proposal of @monio at https://blender.community/c/rightclickselect/J9bbbc.
The changes are:
- Radius of two pixels instead of one - might not be better, though, needs some feedback
- Options to reduce the strength of both ridges and valleys
- Tweaked function for the strength reduction (the original method actually had a local maximum, resulting in a brighter line inside valleys)
- Multiplication for blending instead of overlay, which doesn't work reliably with scene-referred intensities
- Renamed to point out the distinction between it and the SSAO-based cavity overlay

Reviewers: jbakker

Subscribers: linko, monio

Differential Revision: https://developer.blender.org/D3617

Merge remote-tracking branch 'origin/blender2.8' into experimental-build