rm meaningless ":padnewlines" from default header args

* lisp/ob-core.el (org-babel-default-header-args): It is likely that
  someone meant to set :padlines to "yes", but accidentally set
  :padnewlines to "yes".  Either way lets just remove this which
  shouldn't have any functional effect.

lisp/ob-core.el

@@ -478,8 +478,7 @@ specific header arguments as well.")
 
 (defvar org-babel-default-header-args
   '((:session . "none") (:results . "replace") (:exports . "code")
-    (:cache . "no") (:noweb . "no") (:hlines . "no") (:tangle . "no")
-    (:padnewline . "yes"))
+    (:cache . "no") (:noweb . "no") (:hlines . "no") (:tangle . "no"))
   "Default arguments to use when evaluating a source block.")
 
 (defvar org-babel-default-inline-header-args