Switch to sequential rather than concurrent processing of multiple selections

[GregoryBridgett]

I have a library of 300+ items that I'd like to "import" into Todoist to build a reading backlog. However, trying to import them all at once fails catastrophically. Zotero shuts down.

Next, I tried importing a batch of about 30 items. Because it was the first import, the import "section" was created multiple times. This is only an issue if the first use of zotodo involves processing multiple items for which the section isn't created.

Both issues would be solved by sequential rather than concurrent processing of multiple sections. Ideally, it would stop on a failure.