Columnview: Fix the case of #+ content present

* lisp/org-colview.el (org-dblock-write:columnview): Change the
capture of pos to after inserting the original content

The problem is with a block that has content preceding the table.
Upon recreating the content, the `pos' gets set to the beginning of
this content instead of the table.  Later calls to
`org-table-recalculate' or `org-table-align' will fail because the
point is not at a table.

This patch moves the capture of `pos' to right before the insertion of
the table.

TINYCHANGE
Patch by Benjamin Beckwith

lisp/org-colview.el

@@ -1306,10 +1306,10 @@ PARAMS is a property list of parameters:
 			    (if (eq 'hline x) x (cons "" x)))
 			  tbl))
 	(setq tbl (append tbl (list (cons "/" (make-list nfields "<>"))))))
-      (setq pos (point))
       (when content-lines
 	(while (string-match "^#" (car content-lines))
 	  (insert (pop content-lines) "\n")))
+      (setq pos (point))
       (insert (org-listtable-to-string tbl))
       (when (plist-get params :width)
 	(insert "\n|" (mapconcat (lambda (x) (format "<%d>" (max 3 x)))