* Rename to `sortUserSkins` to convey meaning better.
* Sort in-place instead of slicing the list.
* Change to `void` to avoid misleading users that the method returns
a new list instance.
* Fix typo in comment.
The previous code was very brittle - it was not always updating
properly, and seems to have worked either by a carefully crafted set of
circumstances, or just plain coincidence.
Having this be a get-only property avoids potential error in the future
caused by not updating the index properly, at the expense of an added
linear lookup.