Make data retrieval less greedy

[mvexel]

Currently we retrieve data greedily using these queries:

https://github.com/mvexel/meetyourmappers/blob/master/meetyourmappers/views.py#L13-L14

This results in 'stray' data being considered due to recursion. Here's a pretty extreme example, the actual bounding box was a pretty small area around Bow, East London:

@mmd-osm what would be a non-greedy alternative that would clip data to exactly what is inside a bounding box or an OSM area boundary?

[mmd-osm]

I think you could try a query based on the /map call, which assures that all nodes and ways inside your bbox are contained in the result: https://github.com/drolbr/Overpass-API/blob/master/src/cgi-bin/map#L27:

That's:
(node({s}, {w}, {n}, {e});way(bn);node(w););(._;(rel(bn)->.a;rel(bw)->.a;);rel(br););out meta;
or:
(node(area:{});way(bn);node(w););(._;(rel(bn)->.a;rel(bw)->.a;);rel(br););out meta;