Add matching mode "closed way contains element"

[jpear1]

I apologize if this has already been requested elsewhere, but I wasn't able to find any tickets talking about this feature.

It would be very helpful if conflation offered a match mode to match closed ways with an element it contains. My imagined use case is merging buildings and address nodes, but there may be other use cases as well.

This would allow me to avoid a problem I've encountered using conflation where an address for an actual building that hasn't yet been mapped in OSM is matched with a nearby mapped building with no real address (like a shed).

A problem that this match mode would face is multiple equally-weighted matches. There may be cases where this makes sense to resolve randomly, but in the case of address nodes and buildings, it would be very nice to have an option to ignore non-deterministic matches. Sometimes buildings have multiple address nodes in them because they're totally separated rooms, and none of them are more important than the other (town houses for example).

This post gives an algorithm for testing whether a node is contained in a polygon, maybe it'll be helpful: ​http://www.alienryderflex.com/polygon/.

[skyper]

Note: utilsplugin2 already has code for selecting inside area. Maybe it can be used as the plugin is already required.