Merge branch 'master' into temp-ui-tweaks

Merge branch 'master' into temp-ui-tweaks

# Conflicts:
# source/blender/editors/animation/time_scrub_ui.c

Merge branch 'master' into temp-ui-tweaks

# Conflicts:
# source/blender/editors/animation/time_scrub_ui.c

Merge branch 'master' into temp-ui-tweaks

Merge branch 'master' into temp-ui-tweaks

UUID: fix seeding the RNG clock on macOS

On Apple machines, call `clock_gettime()` instead of `timespec_get()`.

macOS only introduced `timespec_get()` in version 10.15 (introduced
approx two years ago, so in 2019), even though the function is from C11.

UUID: include 'seconds' field of current time in RNG seed

XOR the 'seconds' and 'nanoseconds' fields of the current time to seed the
RNG used for generating random UUIDs. This ensures a better seed just in
case the clock as no sub-second resolution.

make_update: Fix case where a sub-module would not have required branch.

Issue revealed by rB546314fc9669 change, also error itself exited before
that commit.

Now we do accept git command to fail when trying to checkout the
specified branch from sub-modules, and only actually error in case the
fall-back branch (aka master) cannot be properly checked out.

Thanks fot Ray molenkamp (@LazyDodo) for report and initial patch
(D12560).

Cleanup: UUID, prevent "missing braces" warning on macOS

Add braces around initialization of sub-objects, as per the warning
suggestion on macOS.

No functional changes.

Cleanup: spelling

Geometry Nodes: new Realize Instances node

This node has a simple geometry input and output.
If the input geometry contains instances, they will be realized
into actual geometry. When there are many instances, this can
be very slow and memory intensive. Generally, instances should
only be made real when necessary, e.g. when every instance
should be deformed independently.

Differential Revision: https://developer.blender.org/D12556

UI: rename "Save Screenshot (Area => Editor)"

The term "area" isn't normally exposed in the UI.

Geometry Nodes: support Noise Texture node

This makes the Noise Texture node available in geometry nodes.
It should behave the same as in shader node, with the exception
that it does not have an implicit position input yet. That will
be added separately.

Differential Revision: https://developer.blender.org/D12467

GPencil: Change Rotation tooltip

The tooltip was not clear about in what shading modes works.

Related to T91467

GPencil: Fix error in previous commit

By error I commited the previous version.

Build: change make update to not print errors regarding submodule branches

Instead of trying to checkout non-existent branches and getting confusing fatal
error prints, check if the branch exists first.

Ref D12560

Fix T91511: GPencil weight_get and Vertex Groups not working at expected

The API was checking the number of total weights with the first point of the stroke and this was not valid because each point can have different number of weight elemnts,

Geometry Nodes: support Set Position node on instances

Previously, the node would always realize instances implicitly.
Now it can change the position of entire instances.
The Realize Instances node can be used before if the old
behavior is required.

Differential Revision: https://developer.blender.org/D12555

Cleanup: spelling (correct c5c8c68eec93e57ed46be4371d8831e2f0fe3fe2)

"iff" was intended as "if and only if". while exact use of abbreviations
isn't clear cut, I assumed this was a typo & it's not used anywhere
else in source/, expand to "only if" (suggested by Sybren).

UUID: add nil value for UUIDs

Add `BLI_uuid_nil()` that returns the nil UUID (used to indicate "not
set") and `BLI_uuid_is_nil(uuid)` to do an equality test with the nil
value.