Tweak UI message of Ruler tool.

It's much simpler to just click on one end, than dragging it outside of
view. ;)

Related to T59084.

Fix T58993: Duplicating after setting a rigid body world crashes Blender.

There is no guarantee that object in rigidbody collection already have a
valid rgigidbody data when rebuilding deg relations, that is often
generated on-the-fly by actual rigid body simulation.

Note that this can be an issue when generating deg relations I guess...
But at least it won't crash anymore.

Proper fix for rigidbody collections's objects missing rb data.

We cannot let those data be generated on-the-fly in RBW evaluation
anymore, since those would be added to CoW eval object and never ported
back to orig objects.

We *could* get orig objects in eval code, of course, but as in
constratints, this is not really threadsafe and future proof, depsgraph
evaluation should really write back to orig data as little as possible.

So instead, add code to ensure required data is generated to objects
when their collection is added to rigidbody world.

Note that we *may* want to clean that up once collection is no more used
by RB? On the other hand, people might want to keep those data around to
be able to switch between different setups easily... So think it's OK to
keep them at least for now.

Cleanup: Someone forgot again to do the versioning_280 handling when bumping subversion.

Seriously... There is no point in having those subversions if one does
not take advantage of them to reduce doversion work on file load! Now we
have to raise subversion again just for that. :(

Merge branch 'master' into blender2.8

Conflicts:
source/blender/makesrna/intern/rna_dynamicpaint.c

Fix T59059: Blender crashing after adding particle system and dynamic paint (Brush).

Looks like this bug has been there since ages (at least present before
2.79 official release...).

Fix modifiers evaluation outside of depsgraph/CoW context.

Fix T58237: Exporters: Curve Modifier not applied when "apply modifiers" are selected.
Fix T58856: Python: "to_mesh" broken in 2.8.

...And many other cases... ;)

Thing is, we need target IDs to always be evaluated ones (at least I
cannot see any case where having orig ones is desired effect here).
Depsgraph/Cow system ensures us that when modifiers are evaluated by it,
but they can also be called outside of this context, e.g. when doing
binding, or object conversion...

So we need to ensure in modifiers code that we actually are always
working with eval data for those targets.

Note that I did not touch to physics modifiers, those are a bit touchy
and rather not 'fix' something there until proven broken!

Cleanup/refactor binding code for MeshDeform modifier.

We had two different ways of doing it, SurfaceDeform and LaplacianDeform
would do it through a special modifier stack evaluation triggered from
binding operator, while MeshDeform would do it through a regular
depsgraph update/eval (also triggered from its binding op).

This enforces the later to search back for orig modifier data inside
modifier code (to apply binding on that one, and not on useless CoW
one).

Besides the question of safety about modifying orig data from threaded
despgraph (that was *probably* OK, but think it's bad idea in general),
it's much better to have a common way of doing that kind of things.

For now it remains rather dodgy, but at least it's reasonably consistent
and safe now.

This commit also fixes a potential memleak from binding process of
MeshDeform, and does some general cleanup a bit.

Cleanup/refactor binding code for MeshDeform modifier.

We had two different ways of doing it, SurfaceDeform and LaplacianDeform
would do it through a special modifier stack evaluation triggered from
binding operator, while MeshDeform would do it through a regular
depsgraph update/eval (also triggered from its binding op).

This enforces the later to search back for orig modifier data inside
modifier code (to apply binding on that one, and not on useless CoW
one).

Besides the question of safety about modifying orig data from threaded
despgraph (that was *probably* OK, but think it's bad idea in general),
it's much better to have a common way of doing that kind of things.

For now it remains rather dodgy, but at least it's reasonably consistent
and safe now.

This commit also fixes a potential memleak from binding process of
MeshDeform, and does some general cleanup a bit.

Minor cleanup in Laplacian deform modifier DNA code.