Now defaults to the /usr/share/dict/american-english dictionary which is
probably found on many Linux systems today (avoiding the need to dig up a word
file on the interwebs). On Debian/Ubuntu, you can 'apt-get install wamerican'.
Added a configurable regexp to filter the word list down to reasonable words.
Defaults to allow lowercase a-z only, therefore filtering out proper names,
hyphenations, contractions, and words with accented characters like "adiós".
(But hopefully still supporting non-English users by allowing this to be
changed.)
