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
This function is more expansive than the simpler `rna_ensure_property()`
one, and should only be used when IDProperty data is actually needed.
If one only needs to ensure it has a valid PropertyRNA pointer,
`rna_ensure_property()` is much more efficient.
Also add compiler warnings when results of those functions are unused,
this should never be the case.
Introduce new PropertyRNAOrID structure, storing most useful data about
an 'opaque' PropertyRNA in relation with a given PointerRNA struct.
It deals with all the three cases (pure static RNA, runtime RNA where
data is actually stored in IDProperties, and pure IDProperties, aka
custom data.
Now, custom props defined as overriddable can be overridden, saved,
reloaded, etc. That fixes the last main issue with them.
Note that custom props still have a lot of glitches and weirdness in
their overriding behavior, but for now the most important is finally
achieved, will let them rest and settle a bit, those have been
incredibly painful to tame... :(
That file was getting out of control, now comparison/override RNA code is
in `rna_access_compare_override.c`. 1K lines of code for now, but that
area is likely to grow more in the future...
Note that we can probably split more out of `rna_access.c`, but for now
that will do.
