DataProcessor data loss issue

[k8n]

DataProcessor fails to call the API with an update when a prior update operation for the item with the same ID is currently in-flight.

https://github.com/webix-hub/webix/blob/2f6e35923f8d8f9886cff09ee0abc02dd886a8b5/sources/load/dataprocessor.js#L236

This is especially problematic when working with a datatable with the autoupdate on over an unreliable or slow network connection.

Suppose a datatable update results in an API call to update the backend. Suppose the API call is delayed and takes 2 seconds to complete. If another update event comes from the datatable while this API call is in flight, Webix will ignore the update, will not commit the change to the backend.