TAGGING REVIEW

Reviewed by GB/HB. Good to go.

HISTORICAL DISCUSSION
Chatham Islands Imported: 5/5 Glen
http://wiki.openstreetmap.org/wiki/Scrub
LINZ defines this layer as <3m high, should we call it height=3m?
(3m scrub is a lot for a tramper to contemplate so maybe not)

how to make it more distinct from the mixed_scrub_poly layer which
is taller, and scat_scrub which is shorter?