This replaces header include guards with `#pragma once`.
A couple of include guards are not removed yet (e.g. `__RNA_TYPES_H__`),
because they are used in other places.
This patch has been generated by P1561 followed by `make format`.
Differential Revision: https://developer.blender.org/D8466
That one was a bit more complicated, and is still only partial refactor
(ultimately we want to have a foreach_id callback in SpaceType itself I
think...).
Part of T74960 (and hence T75724).
This commit only adds the basics helper code, and alter some internal libquery
code to use it.
Porting each IDType to the new system will be done gradually from there,
to allow better detection and handling of potential issues.
Differential Revision: https://developer.blender.org/D7598
'Private' can be a rather confusing term, especially when considering
its meaning in programming languages.
So now root node trees and master collections are 'embedded' IDs
instead.
The former is always a real, in-Main data-block, while the later, when
different, should be one of those embedded 'private' IDs (like root node
ree or master collection).
Handling those through different ways /might/ be needed sometimes, but
in most case this is just a nest of issues, since you can easily forget
to take them into account.
Note that this should be a 'non-functional' change, as this new behavior
is not used anywhere yet.
Using a struct here allows to change given parameters to the callbacks
without having to edit all callbacks functions, which is always noisy
and time consuming.
