Scan bigger chunks

[narc0tiq]

Configure a linking distance for ores (Factorio may already have this property) and search larger areas with find_entities_filtered to look for connected ores from the same patch.

Compare performance with the single-tile, single entity search we do right now. I suspect it will be faster to iterate the larger result than to search N times.

[narc0tiq]

Factorio does already have the property, but it exists only in the data stage: resource_patch_search_radius (default 3) controls how the mouseover counts are done on the map.

I suppose we'll have to have our own search radius (but 3, aka a 5x5, seems like a good start).

[narc0tiq]

See also #111, which is about changing how scanning works by providing a non-scanning site addition process