allow 'footway', 'highway', 'railway' when generating areaKeys
remove building_area for school, kindergarden, etc

These keys should not automatically get building=yes added:
amenity/school, amenity/kindergarden,
tourism/picnic_site, tourism/theme_park

Also renamed to "School Grounds" and "Kindergarden Grounds"
for clarity..
Revert "allow 'footway', 'highway', 'railway' when generating areaKeys"

This reverts commit a8d6dcbbc1d28c4b832b1af4f8716c079e4e6189.

Conflicts:
	js/id/core/area_keys.js
revert autogenerated area_keys too
add crop field for farmland, add trees field for orchard..
add preset for landuse=landfill
add the hoops=* field to the basketball preset
add smoking field for many presets under amenity, building, office, tourism..
Merge branch 'bhousel' of github.com:bhousel/iD into bhousel