Revert changes to BLI_heap

Add intial work on possion disk distribution

Fix paste f-curve modifiers default "Only Active" value

The tooltip implies that this option should be off per default instead
of on. Some talking with the animators at the studio and in the
animation module confirmed that this seems to be the most logical
default.

Add a Un-Bake FCurves operator

We already had the ability to bake fcurves but no way to convert the
baked result back without using python. This patch adds and operator
that is available now next to the bake operator in the drop down menu,

Reviewed By: Sybren

Differential Revision: http://developer.blender.org/D6379

Merge branch 'blender-v2.91-release'

Fix T81844: Change Bone Layers fails in Pose Mode

When selecting multiple layers, the redo operator might not correctly
update the pose data. To make sure it is in a good state we have to
ensure that the pose data is good.

Reviewed By: Bastien

Differential Revision: http://developer.blender.org/D9354

Cleanup: General comment style clean up of graph_edit.c and fcurve.c

No functional changes.

Reviewed By: Sybren A. Stüvel

Differential Revision: http://developer.blender.org/D7850

Fix libmv eigen alignment issues when compiling with AVX support

There would be eigen alignment issues with the custom libmv vector
class when compiling with AVX optimizations. This would lead to
segfaults.

Simply use the std::vector base class as suggested by the old TODO in
the class header.

Reviewed By: Sergey

Differential Revision: http://developer.blender.org/D8968

Fix running tests when building without portable install.

Fix blender constraints automated tests when using march=native

More agressive optimization made the results differ a bit more than the
current error margin would allow. Bump the error margin to be 1e-6
instead of the previous 0.5e-7.