Merge branch 'master' into undo-experiments

Merge branch 'master' into asset-engine

undo experiments: actually write at leat one memchunck per ID.

Checked that before, but missed the fact that the flush was done after a
whole ID type process in the main saving loop, now we actually do it
after every ID when using mem undo file saving.

Besides fixing the stupid issue with lots of unchanged IDs being
detected as changed when reading back the undo step, this should also
help reduce undo memory usage in some cases (although I could not detect
that with some quick test...).

Merge branch 'master' into undo-experiments

Undo experiments: remove assert that can only be true in some specific cases.

Undo experiments: proof-of-concept of reusable depsgraph across undo steps.

This is still very sketchy, but seems to work in basic cases. useless
currently, though, as objects are always changed still currently in undo
steps...

Not Yet Working (r)

Merge branch 'master' into undo-experiments

Fix T71199: Child-parent relationships arent kept after you make instances real.

Comparison function of the of the parent ghash was not fully correct,
could lead to some false positives in some cases...

Fix T70789: Using Remove Single Override breaks file loading (crash).

We only need to refine rna pointer for actual collection properties,
other arrays we handle directly the the appy callback.

Fix T70778: Library Override dissabled after re-instancing same collection in different scene.

Very stupid mistake in own new generic ID lib_link function, that would try
to link ID pointers for all data-blocks, not only those actually needing it.