* lisp/replace.el (query-replace-from-to-separator): Move propertize

* lisp/replace.el (query-replace-from-to-separator): Move propertize

and char-displayable-p test to query-replace-read-from.
Add choice nil to disable this feature.
(query-replace-read-from): Don't reevaluate custom setting.
Use char-displayable-p to test the first non-whitespace character
in query-replace-from-to-separator, use " -> " when fails.
Add prompt for the case when separator is nil but
query-replace-defaults is non-nil.
Remove unused test for regexp-flag.
Thanks to Thierry Volpiatto <thierry.volpiatto@gmail.com>