Standardize on American spellings.

Full internationalization would be much cooler, but that's never going
to happen.  Given that, this will at least prevent folks from constantly
having to look and switch between typing "armor" and "armour", depending
on which zone each item originated in, etc.

I could flip these either way, but a survey of the current state shows
that about 80% of the mixed cases use the American spellings, while 20%
use the British.  And, most words *only* exist in this data in their
American forms.  So, it seems the majority prefer these spellings.

In case anyone likes trivia:
* The most common mixed words in here were "armour" and "colour", each of
  which occured about half as often as "armor" and "color", respectively.
* The most British word in here was "theatre" (including other forms),
  which occured about twice as often as "theater".

This stanardizes all of these (and other forms of these same words):
* armour -> armor
* colour -> color
* favour -> favor
* honour -> honor
* civilise -> civilize
* centre -> center
* theatre -> theater
* defence -> defense
* offence -> offense
* realise -> realize

lib/world/wld/54.wld

@@ -158,7 +158,7 @@ S
 Southeastern Market Square~
    In this corner of the market some of the largest warriors in the land
 tower over you.  It is easy to understand why they hang out here once you
-notice the weapon shop and the armoury close by.  Perhaps you might stop
+notice the weapon shop and the armory close by.  Perhaps you might stop
 in and take a look at the wares these shops have to offer.
 ~
 54 0 0 0 0 1