data overlay with miriam ids

it takes much time to obtain the results, and if it's too much time 504 is returned

added performance label

created branch 238-data-overlay-with-miriam-ids

mentioned in merge request !195 (merged)

closed via merge request !195 (merged)

closed via commit 59ddae65

!195 (merged) improves performance ~4 times in big examples (1k queries for 4k elements on the map).

It can be improved more by algorithmic changes (reducing O(nm) time complexity to O(nlogm) time complexity), but we leave it for now.

mentioned in commit 59ddae65