[tz] [PROPOSED] Remove invented North American abbreviations

[Paul Eggert]

Brian Inglis wrote:
> http://www.st-pierre-et-miquelon.com/en/faq/
> "Time Zone
> Saint-Pierre & Miquelon is part of the WTG [sic - s/b WGT] Time Zone (UTC-3).

Hah! Their French-language page uses "WTG" too -- shouldn't that be "HGO"? (:-)

Since "WGT" is our invention, I'm not inclined to use it for St Pierre & 
Miquelon. When I get around to cleaning up "europe" I can remove "WGT" from the 
Greenland entries.

> does using the Canada rule require it to stay in northamerica?

Yes, for the benefit of people who run 'zic northamerica' and/or 'zic europe'.