(ispell-init-process): Include the used dictionary in ispell process

(ispell-init-process): Include the used	dictionary in ispell process
start message.
(ispell-internal-change-dictionary): When flyspell-mode is active and
dictionary is changed, make sure ispell process is restarted and
flyspell word cache cleared out for the current buffer.
(ispell-change-dictionary): Make sure flyspell word cache is cleared
out in all buffers with active flyspell mode when dictionary is globally
changed.  Call ispell-internal-change-dictionary after dictionary change.