Get annotations and who used them for a set of skeletons.

Get annotations and who used them for a set of skeletons.

This method focuses only on annotations linked to skeletons and is likely to be faster than the general query. Returns an object with two fields: "annotations", which is itself an object with annotation IDs as fields, giving access to the corresponding annotation names. And the field "skeletons" is also an object, mapping skeleton IDs to lists of annotation-annotator ID pairs. Also, as JSON separator a colon is used instead of a comma.