org-element: Fix parsing of planning in inline tasks

* lisp/org-element.el (org-element--next-mode): Line following an
  inlinetask can be a planning.
* testing/lisp/test-org-element.el (test-org-element/inlinetask-parser):
  Update test.

Reported-by: Gregor Zattler <telegraph@gmx.net>
<http://permalink.gmane.org/gmane.emacs.orgmode/101958>

lisp/org-element.el

@@ -4183,6 +4183,7 @@ otherwise.  Modes can be either `first-section', `item',
   (if parentp
       (case type
 	(headline 'section)
+	(inlinetask 'planning)
 	(plain-list 'item)
 	(property-drawer 'node-property)
 	(section 'planning)

testing/lisp/test-org-element.el

@@ -1221,17 +1221,28 @@ Contents
       ;; Planning info.
       (should
        (org-test-with-temp-text "
-*************** Task
+*************** Task<point>
 DEADLINE: <2012-03-29 thu.>
 *************** END"
-	 (forward-line)
 	 (org-element-property :deadline (org-element-at-point))))
-      (should-not
+      (should
+       (eq 'planning
 	   (org-test-with-temp-text "
 *************** Task
+<point>DEADLINE: <2012-03-29 thu.>
+*************** END"
+	     (org-element-type (org-element-at-point)))))
+      (should-not
+       (org-test-with-temp-text "
+*************** Task<point>
 DEADLINE: <2012-03-29 thu.>"
-	 (forward-line)
 	 (org-element-property :deadline (org-element-at-point))))
+      (should-not
+       (eq 'planning
+	   (org-test-with-temp-text "
+*************** Task
+<point>DEADLINE: <2012-03-29 thu.>"
+	     (org-element-type (org-element-at-point)))))
       ;; Priority.
       (should
        (eq