Especially for importing any feeds and deleting feeds that create nodes through the UI we should Batch API
- Ideally we can implement this on the FeedsImporter level
- Keep the overhead for FeedsPlugins low
- Make sure fallback with JS is clean
- How can we do incremental import?
-- CSV parser could read X items from file
-- XML parser could parse all file, but only pass on X
-- Both would require an internal iterator that can be incremented and reset.
-- Batching may be supported only by some parsers.