Use replace-buffer-contents to reformat buffer

According to `replace-buffer-contents` documentation this function
replaces buffer contents in smarter way. Especially interesting part:

    As far as possible the replacement is non-destructive,
    i.e. existing buffer contents, markers, properties, and overlays
    in the current buffer stay intact.

One example where some properties are preserved is when origami-mode
is used on the buffer to collapse some regions. After this change
collapsed regions stay collapsed after reformatting

format-all.el

@@ -1077,9 +1077,11 @@ LANGUAGE is the language ID of the current buffer, from
                     ((not (equal f-output t))
                      (setq reformatted-by
                            (append reformatted-by (list f-name)))
-                     (let ((inhibit-read-only t))
-                       (erase-buffer)
-                       (insert f-output))
+                     (let ((helper-buffer (generate-new-buffer "*format-all-output*")))
+                       (with-current-buffer helper-buffer
+                         (insert f-output))
+                       (replace-buffer-contents helper-buffer)
+                       (kill-buffer helper-buffer))
                      (setq f-status :reformatted)))
               (run-hook-with-args 'format-all-after-format-functions
                                   f-name f-status)