[Tagging] Traffic training area ("Verkehrsübungsplatz" in German)

[Tom Pfeifer]

Reading the recent wiki-talk by Dieterdreist, the proposed "driver_training" goes in the right 
direction, however I would drop the "area" suffix and the "children" prefix to keep the value compact.

The age group can be described with additional tags such as min_age= or max_age, the vehicle with 
common access tags like bicycle=yes and motorcar=yes.

Thus: amenity=driver_training

tom