These previously returned an itemID, but now that new saved items can be edited
without a refetch, they should just return the new item.
(Possible I missed a few spots where these are called.)
Change all attachment functions to take parameter objects, including a
'collections' property to assign collections. (Previously, calling code
assigned collections separately, which required a nested transaction,
which is no longer possible.)
Fixes#723, Can't attach files by dragging
