look: use WORDLIST environment variable to find word list

look: use WORDLIST environment variable to find word list

The WORDLIST is the same hunspell(1) and ispell(1) uses to achieve the same.
Apparently aspell(1) does not work with files like traditional dict lists.

Reference: https://github.com/hunspell/hunspell/blob/master/man/hunspell.1#L388
Reference: http://www.skrenta.com/rt/man/ispell.1.html
Reference: http://aspell.net/man-html/Creating-an-Individual-Word-List.html#Creating-an-Individual-Word-List
Signed-off-by: Sami Kerola <kerolasa@iki.fi>