* backzone: Explain Zone columns.
Rename fields of Link lines for clarity.

* zic.8, zoneinfo2tdf.pl: Change names of Link line fields to be more
descriptive and more like the parameters of 'ln'.  LINK-FROM becomes
TARGET, and LINK-TO becomes LINK-NAME.
* backward: Add a '# Link' header.
* europe, northamerica: Add a few '# Zone' headers where needed.
* NEWS: Document this.
More spacing fixes within UNTIL fields.
Better align end-of-line comments within Zones.

Per a suggestion from Alan Barrett:
http://mm.icann.org/pipermail/tz/2014-August/021416.html

Also some minor commentary changes to fit within 80 columns.