`ispell-internal-change-dictionary' when not needed.
(ispell-change-dictionary): Use this argument and call
`ispell-internal-change-dictionary' after the possible change to
`ispell-local-dictionary'.
(ispell-internal-change-dictionary): Check for a change in personal dictionary
use too.
Cosmetic changes from Agustín Martín <agustin.martin@hispalinux.es>.