Since internally a building is identified as a GeoDataBuilding we don't need to store the building tag anymore. Hence its parsing and storage should be removed from the code.

• Cathredals etc still have their icons

• Selecting a cathedral tells that you selected a cathredal, not a building (like it does currently)

• Tile creation still works, also for buildings (tile creation uses the same osm parser as the Marble Maps client).

• Building rendering works as before