fix: javascript Paginator

Paginator had batchSize option which supposedly load pages in batches,
but it didn't and generally broken. It was impossible to set it to 0,
i.e. disable batching, setting it to 1 would load 2 pages at once
instead of 1, and it only gave effect for 1st load, subsequent requests
for next page would load pages 1 by 1. So the only effect it gave is
that after user opened an url, Paginator would load 3 (!) next pages in
background.