Allow white spaces between the counter and the check-box in an item

* lisp/org-list.el (org-list-full-item-re): allow counter and
  check-box to be separated by white spaces.
(org-list-struct-apply-struct): reflect changes made to
`org-list-full-item-re'.
* lisp/org-html.el (org-html-export-list-line): recognize spaces
  between counter and check-boxes as valid.
* lisp/org-docbook.el (org-export-docbook-list-line): ditto.

lisp/org-docbook.el

@@ -1398,7 +1398,7 @@ the alist of previous items."
      ;; At an item: insert appropriate tags in export buffer.
      ((assq pos struct)
       (string-match (concat "[ \t]*\\(\\S-+[ \t]*\\)"
-			    "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[a-zA-Z]\\)\\]\\)?"
+			    "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[a-zA-Z]\\)\\][ \t]*\\)?"
 			    "\\(?:\\(\\[[ X-]\\]\\)[ \t]+\\)?"
 			    "\\(?:\\(.*\\)[ \t]+::\\(?:[ \t]+\\|$\\)\\)?"
 			    "\\(.*\\)")

lisp/org-html.el

@@ -2531,7 +2531,7 @@ the alist of previous items."
      ((assq pos struct)
       (string-match
        (concat "[ \t]*\\(\\S-+[ \t]*\\)"
-	       "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[A-Za-z]\\)\\]\\)?"
+	       "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[A-Za-z]\\)\\][ \t]*\\)?"
 	       "\\(?:\\(\\[[ X-]\\]\\)[ \t]+\\)?"
 	       "\\(?:\\(.*\\)[ \t]+::\\(?:[ \t]+\\|$\\)\\)?"
 	       "\\(.*\\)") line)

lisp/org-list.el

@@ -370,8 +370,8 @@ specifically, type `block' is determined by the variable
 It depends on `org-empty-line-terminates-plain-lists'.")
 
 (defconst org-list-full-item-re
-  (concat "^[ \t]*\\(\\(?:[-+*]\\|\\(?:[0-9]+\\|[A-Za-z]\\)[.)]\\)[ \t]*\\)"
-	  "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[A-Za-z]\\)\\]\\)?"
+  (concat "^[ \t]*\\(\\(?:[-+*]\\|\\(?:[0-9]+\\|[A-Za-z]\\)[.)]\\)[ \t]+\\)"
+	  "\\(?:\\[@\\(?:start:\\)?\\([0-9]+\\|[A-Za-z]\\)\\][ \t]*\\)?"
 	  "\\(?:\\(\\[[ X-]\\]\\)[ \t]+\\)?"
 	  "\\(?:\\(.*\\)[ \t]+::\\(?:[ \t]+\\|$\\)\\)?")
   "Matches a list item and puts everything into groups:
@@ -1647,11 +1647,13 @@ Initial position of cursor is restored after the changes."
 		((and (match-string 3) new-box)
 		 (replace-match new-box nil nil nil 3))
 		((match-string 3)
-		 (goto-char (or (match-end 2) (match-end 1)))
-		 (looking-at "\\[[ X-]\\][ \t]+")
-		 (replace-match ""))
-		(t (goto-char (or (match-end 2) (match-end 1)))
-		   (insert (concat new-box " "))))
+		 ;; (goto-char (or (match-end 2) (match-end 1)))
+		 ;; (skip-chars-backward " \t")
+		 (looking-at ".*?\\([ \t]*\\[[ X-]\\]\\)")
+		 (replace-match "" nil nil nil 1))
+		(t (let ((counterp (match-end 2)))
+		     (goto-char (if counterp (1+ counterp) (match-end 1)))
+		   (insert (concat new-box (unless counterp " "))))))
 	       ;; c. Indent item to appropriate column.
 	       (unless (= new-ind old-ind)
 		 (delete-region (goto-char (point-at-bol))