Rewrite: SwingMapViewer

[emux]

Hi Thilo,

Excellent job with the SwingMapViewer!
I try it with my custom maps (by changing the code at MapViewer) and I have some points:

It would be convenient if we could have here also some options of Android AdvancedMapViewer like:
- Mainly a menu for select the the map file and the xml render theme to load - it would be awesome.
- The option "Tile boundaries" and specially the "Tile coordinates".

- With no preferences saved at registry, if I try to load a custom map file of mine with the corresponding my custom external render theme I get at console:
Exception in thread "MapWorker" java.lang.IllegalArgumentException: tileX must n
        at org.mapsforge.core.model.Tile.<init>(Tile.java:58)
        at org.mapsforge.map.layer.renderer.DependencyCache.removeReferencePoint
        at org.mapsforge.map.layer.renderer.LabelPlacement.removeNonValidateRefe
        at org.mapsforge.map.layer.renderer.LabelPlacement.processFourPointGreed
        at org.mapsforge.map.layer.renderer.LabelPlacement.placeLabels(LabelPlac
        at org.mapsforge.map.layer.renderer.DatabaseRenderer.executeJob(Database
        at org.mapsforge.map.layer.renderer.MapWorker.doWork(MapWorker.java:43)
        at org.mapsforge.map.PausableThread.run(PausableThread.java:140)

and I see no map. But if I load the corresponding mapsforge map (of same area as my custom made) from your download server with the Osmarender internal render theme then I see it. If I zoom in it, so that the preferences can be initialized correctly, and then I load my custom map file with custom external render theme then the load succeeds and I see my custom map.
(My custom map has bounding box and correctly declared start map position and start zoom - I test it successfully at Android AdvancedMapViewer)

- May be it would be better if the saved preferences at registry are being declared per map file. If I change the map file or the preferences are empty the MapViewer could start at start map position and zoom as declared at map file. If they don't exist at map file, the MapViewer can start at map center and a default zoom (12), just like AdvancedMapViewer at Android.

Thanks!