U.S. and Canadian address formats

New mappers in the U.S. keep setting `addr:city` to things like “Cincinnati, Ohio” or “[Cincinnati, OH](http://www.openstreetmap.org/node/2700662035/history)”, or setting `addr:postcode` to “[OH 45011](http://www.openstreetmap.org/node/2576194479/history)” because the Postcode field appears to the right of the City field.

With this change, U.S. addresses now have a State field corresponding to `addr:state` between City and Postcode. I also added Province between City and Postcode for Canadian addresses, since they’re formatted similarly in both English and French.