Issue revealed by own recent cleanup in rB8820ab4, and moticed by
@brecht, thanks.
Note that am not 100% sure whether we should allow call on lib_query
without a proper valid owner_id, for embedded data-blocks. But this can
be investifated later, so far things have been working like that.
'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.
This commit is a full refactor of the grease pencil modules including Draw Engine, Modifiers, VFX, depsgraph update, improvements in operators and conversion of Sculpt and Weight paint tools to real brushes.
Also, a huge code cleanup has been done at all levels.
Thanks to @fclem for his work and yo @pepeland and @mendio for the testing and help in the development.
Differential Revision: https://developer.blender.org/D6293
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.
