* ispell.el (ispell-alternate-dictionary): Use file-readable-p.
Return nil if no word-list is found at default locations.
(ispell-complete-word-dict): Default to nil.
(ispell-command-loop): Use 'word-list' when using lookup-words.
(lookup-words): Use ispell-complete-word-dict or
ispell-alternate-dictionary. Check for word-list availability
and handle errors if needed with better messages (Bug#6539).
(ispell-complete-word): Use ispell-complete-word-dict or
ispell-alternate-dictionary.
fd5539c6de