Issue paginating beyond 10K results

[nonword]

Reported by @ablwr on "?q=war&page=201&per_page=50" query, getting:

"error": "[query_phase_execution_exception] Result window is too large, from + size must be less than or equal to: [10000] but was [10050]. See the scroll api for a more efficient way to request large data sets. This limit can be set by changing the [index.max_result_window] index level setting."

Let's consider using scroll api to use cursors instead of page for deep pagination. Or maybe for all pagination? Investigation required. Need to consider, for example, how to handle expired scroll ids.

https://www.elastic.co/guide/en/elasticsearch/reference/2.4/search-request-scroll.html

https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/api-reference-5-2.html#api-scroll-5-2