(query-replace-interactive): New user option.

(query-replace-interactive): New user option.
(query-replace-read-args): Obey that option--fetch from
search-ring or regexp-search-ring.  New arg regexp-flag.
(query-replace, query-replace-regexp, replace-string)
(replace-regexp): Pass new arg to query-replace-read-args.
(map-query-replace-regexp): Obey query-replace-interactive.