[patch] Initial classes to hold Notes data

[ToeBee]

As discussed on the mailing list, here is the first patch in support of adding OSM notes to core. The patch contains three new classes. Two of them are just the object representation of notes and note comments. The third is the XML parser which handles both the API style XML and the planet dump style XML. I was able to test the dump parser by hardcoding some things in the notes plugin. It successfully loaded all 270+ thousand notes in the current dump. It took 5 minutes to do so but most of that was in the GUI code. Parsing took a few seconds.

One thing I just thought of: Is a List the best data structure to use for holding notes? So far, efficiency hasn't been a big concern since the notes plugin can only talk to the API and the API has a hard limit of 10,000 notes per request. But if we are going to support loading the dump files, things may need tweaking.

[bastiK]

In 7451/josm:

applied #10434 - Initial classes to hold Notes data (patch by ToeBee)

[bastiK]

I don't think efficiency is a primary concern with notes as you usually don't have that many. If you want to quickly find all the notes in a given bounding box, then QuadBuckets is the container that was written exactly for this purpose. It is currently restricted to <T extends OsmPrimitive>, but shouldn't be too hard to generalize to any object that has a LatLon coordinate.