OSM POI Layer Improvements

[taetscher]

This Layer needs some improvements.

Specifically it would be nice if we had a QGIS workflow automated that:

• Gets the latest OSM data via Overpass Query (should be doable from within QGIS)
• Creates a class Attribute and populates the attribute (needed to distinguish icons when drawing the map)
• Dumps all non-essential Attributes (keeps only the Class and Name attributes)
• Saves the layer as a geojson with correct EPSG

The JS part also could do with a few improvements (only after a class attribute was established)

• no popups on POIs without a name attribute