Automatic renaming is now done for dragging of an external file onto an
item (as added in 7cb95f41) as well as dragging as a linked file,
dragging a non-native (not text or HTML) URL, "Attach Link to File…",
"Attach Stored Copy of File…", and "Retrieve Metadata for PDF". It only
applies if a single file is being added and if the parent item has no
non-HTML attachments. By default, the renaming only applies to PDFs, but
this can be changed with the renameAttachmentFiles.automatic.fileTypes
hidden pref.
A new General pref, "Automatically rename attachment files using parent
metadata", controls whether the renaming happens.
Files saved via web translators are renamed regardless of this pref,
because they would often be gibberish otherwise.
Closes#113
f8b41c971c