* Importer will now ask user for a login and password via form and will perform sign-in directly
using credentials rather than oauth
* Signing in this way enables importer to obtain desktop document ID which is now stored for each
item
* It's possible to switch back to the old method (ouath) by setting `import.mendeleyUseOAuth` pref
to `true`.
* New option to only import new items. This options only appears if database contains previously
imported items.
* Importer will now update mendeleyDB:documentUUID on existing items to match value used in Mendeley
Desktop if available
* Importer will no longer create collections when no new items are imported
* Importer will only report number of new items imported on re-import
* Importer will now preserve dateAdded on re-import
Co-authored-by: Dan Stillman <dstillman@zotero.org>
