Fix empty line bug in capture

* lisp/org-capture.el (org-capture-empty-lines-before):
(org-capture-empty-lines-after): Make sure the n=0 does not insert any
newlines.

Marcel van der Boom writes:

> I'm in the process of migrating from org-remember to org-capture.
> Pretty easy going so far, but it seems org-capture adds newlines, which
> I think it should not do.
>
> My (test) capture-template is:
>
> (("t" "Todo" entry
>  (file "~/.outlet/GTD.org")
>  "* TODO %?" :prepend t :empty-lines 0)
>
> with the intention of inserting the captured task on the
> first line of the file ~/.outlet/GTD.org. What happens when I capture
> an task is this:
>
> <beginning of file>
>
> * TODO Captured task
>
> <original first line of file here>
> ....
>
> Both before and after the task is a newline. Also, when capturing and
> cancelling the capture with C-c C-k the newlines remain whereas the
> task is removed.

lisp/org-capture.el

@@ -948,7 +948,7 @@ Point will be after the empty lines, so insertion can directly be done."
   (let ((pos (point)))
     (org-back-over-empty-lines)
     (delete-region (point) pos)
-    (newline n)))
+    (if (> n 0) (newline n))))
 
 (defun org-capture-empty-lines-after (&optional n)
   "Arrange for the correct number of empty lines after the inserted string.
@@ -957,7 +957,7 @@ Point will remain at the first line after the inserted text."
   (org-back-over-empty-lines)
   (while (looking-at "[ \t]*\n") (replace-match ""))
   (let ((pos (point)))
-    (newline n)
+    (if (> n 0) (newline n))
     (goto-char pos)))
 
 (defvar org-clock-marker) ; Defined in org.el