For many years, animators have been complaining about how keyframing a (transform)
property directly would leave them ungrouped, while keyframing them using a Keying Set
would put them into a group based on the name of the keyingset.
This commit attempts to improve (unify + make consistent) the default behaviour:
* All object transforms now get added to an "Object Transforms" group,
regardless of whether they were added individually via buttons or keyingset
* All bone transforms now get added to a group corresponding to the name of the bone
instead of only the ones added via keyingset