2754: Revert Entity::bounds() to returning the definition bounds.

[ericwa]

Add a new Node::cullingBounds() that includes the model bounds.

I need to add some docs, but this is what I had in mind in the comment here: #2754 (comment)

cullingBounds() is always equal or larger than bounds(). Currently, the only place where it differs from bounds() is it includes entity models that extend beyond the entity definition bounds, like monster_boss. The only place it's used is for AABB tree insertions.

Entity::definitionBounds could be dropped and replaced with bounds() now.

I should double check the codebase for any uses of bounds() that should be changed to cullingBounds(), but this seems to work.

Fixes #2754

[ericwa]

That should be everything. Was wondering if we should rename Node::bounds() to Node::gameplayBounds() but maybe bounds is enough.

This stuff: Object::contains, Object::intersects, BoundsIntersectsNodeVisitor, CollectTouchingNodesVisitor, is using Node::bounds() so it will not take into account an arm sticking out of the entity definition bounds. This is what we want for the "Select Touching" command, at least.

[kduske]

I approve of the changes, but object to the naming.

[kduske]

Good to have this clarified finally.