Addresses #16545. Allows for user defined environment variables that
hold paths to wordlists. This is to allow for easy access to wordlists
for users and scripts, (in other distributions a convenient wordlist is
typically found in /usr/share/dict/words or similar). The default
wordlist is the one found in scowl, for no other reason than that's the
one that was mentioned in the linked issue.
It is possible to specify multiple environment variables as well. This
is for users who need multiple wordlists (such as multilingual users).
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