Also ensure it shows this animation correctly when expanding "Versions".
This is done by changing from `notifyDataSetChanged()` to the more
specific `notifyItemRange(Inserted|Removed)`, which ensures the
"Versions" item doesn't get rebuilt midway through an animation.
Also tried a more specific naming scheme for dimens to make it clearer where
they are to be used. This increased the padding on the left/right of the collapsable
lists. It also decreased the padding above/below.
