Prevent invisible characters in keywords

* lisp/org.el (org-fontify-meta-lines-and-blocks-1): Forbid invisible
  characters (e.g. bracket links) in all keywords but TITLE, DATE,
  AUTHOR, CAPTION and EMAIL.  Also remove back-end specific keywords,
  which are treated just like any other regular keyword.

Reported-by: Rasmus <rasmus@gmx.us>
<http://permalink.gmane.org/gmane.emacs.orgmode/95415>

lisp/org.el

@@ -5881,17 +5881,6 @@ by a #."
 	      (dc3 (downcase (match-string 3)))
 	      end end1 quoting block-type ovl)
 	  (cond
-	   ((member dc1 '("+html:" "+ascii:" "+latex:"))
-	    ;; a single line of backend-specific content
-	    (org-remove-flyspell-overlays-in (match-beginning 0) (match-end 0))
-	    (remove-text-properties (match-beginning 0) (match-end 0)
-				    '(display t invisible t intangible t))
-	    (add-text-properties (match-beginning 1) (match-end 3)
-				 '(font-lock-fontified t face org-meta-line))
-	    (add-text-properties (match-beginning 6) (+ (match-end 6) 1)
-				 '(font-lock-fontified t face org-block))
-					; for backend-specific code
-	    t)
 	   ((and (match-end 4) (equal dc3 "+begin"))
 	    ;; Truly a block
 	    (setq block-type (downcase (match-string 5))
@@ -5943,18 +5932,14 @@ by a #."
 	     (if (string-equal dc1 "+title:")
 		 '(font-lock-fontified t face org-document-title)
 	       '(font-lock-fontified t face org-document-info))))
-	   ((or (equal dc1 "+results")
-		(member dc1 '("+begin:" "+end:" "+caption:" "+label:"
-			      "+orgtbl:" "+tblfm:" "+tblname:" "+results:"
-			      "+call:" "+header:" "+headers:" "+name:"))
-		(and (match-end 4) (equal dc3 "+attr")))
-	    (org-remove-flyspell-overlays-in
-	     (match-beginning 0)
-	     (if (equal "+caption:" dc1) (match-end 2) (match-end 0)))
-	    (add-text-properties
-	     beg (match-end 0)
-	     '(font-lock-fontified t face org-meta-line))
-	    t)
+	   ((equal dc1 "+caption:")
+	    (org-remove-flyspell-overlays-in (match-end 2) (match-end 0))
+	    (remove-text-properties (match-beginning 0) (match-end 0)
+				    '(display t invisible t intangible t))
+	    (add-text-properties (match-beginning 1) (match-end 3)
+				 '(font-lock-fontified t face org-meta-line))
+	    (add-text-properties (match-beginning 6) (+ (match-end 6) 1)
+				 '(font-lock-fontified t face org-block)))
 	   ((member dc3 '(" " ""))
 	    (org-remove-flyspell-overlays-in beg (match-end 0))
 	    (add-text-properties
@@ -5962,9 +5947,10 @@ by a #."
 	     '(font-lock-fontified t face font-lock-comment-face)))
 	   (t ;; just any other in-buffer setting, but not indented
 	    (org-remove-flyspell-overlays-in (match-beginning 0) (match-end 0))
-	    (add-text-properties
-	     beg (match-end 0)
-	     '(font-lock-fontified t face org-meta-line))
+	    (remove-text-properties (match-beginning 0) (match-end 0)
+				    '(display t invisible t intangible t))
+	    (add-text-properties beg (match-end 0)
+				 '(font-lock-fontified t face org-meta-line))
 	    t))))))
 
 (defun org-fontify-drawers (limit)