Ongoing task for improving poi-mapping.
Related to #728.
POI mapping: remove empty tag #736
POI mapping: fix incorrect tagging #736
POI mapping: improvements by Christian Kernbeis #736
Annotation by Christian Kernbeis regarding his improvements:
"IMO this POI-Database is intended to find specific places/pois so IMO it does'nt make much sense to include paste_bins, cycle_barriers, public visible clocks aso (as long as the poi-database is'nt bound to the theme, completely replacing the icons bound to the map itself).
Tags like vending_machines should be more specific (vending=)."
POI mapping: fix tags #736