The `BKE_animsys.h` and `anim_sys.c` files already had a an "AnimData
API" section. The code in that section has now been split off, and
placed into `BKE_anim_data.h` and `anim_data.c`.
All files that used to include `BKE_animsys.h` have been adjusted to
only include the animation headers they need (sometimes none).
No functional changes.
Only the volume object is exposed in the user interface. It is based on OpenVDB
internally. Drawing and rendering code will follow in another commit.
https://wiki.blender.org/wiki/Source/Objects/Volume
https://wiki.blender.org/wiki/Reference/Release_Notes/2.83/Volumes
Hair and PointCloud object types are hidden behind a WITH_NEW_OBJECT_TYPES
build option. These are unfinished, and included only to make it easier to
cooperate on development in the future and avoid tricky merges.
https://wiki.blender.org/wiki/Source/Objects/New_Object_Types
Ref T73201, T68981
Differential Revision: https://developer.blender.org/D6945