ox-koma-letter: Allow to disable place locally

* contrib/lisp/ox-koma-letter.el (koma-letter):
(org-koma-letter--build-settings): Allow to disable place locally.

Whenever OPTION keyword contains a "place" item or PLACE keyword is used
in the buffer, set KOMA option place after LCO inclusion.

Reported-by: Alan Schmitt <alan.schmitt@polytechnique.org>
<http://permalink.gmane.org/gmane.emacs.orgmode/101010>

contrib/lisp/ox-koma-letter.el

@@ -435,7 +435,8 @@ e.g. \"title-subject:t\"."
     (:inbuffer-with-backaddress nil "backaddress" 'koma-letter:empty)
     (:inbuffer-with-email nil "email" 'koma-letter:empty)
     (:inbuffer-with-foldmarks nil "foldmarks" 'koma-letter:empty)
-    (:inbuffer-with-phone nil "phone" 'koma-letter:empty))
+    (:inbuffer-with-phone nil "phone" 'koma-letter:empty)
+    (:inbuffer-with-place nil "place" 'koma-letter:empty))
   :translate-alist '((export-block . org-koma-letter-export-block)
 		     (export-snippet . org-koma-letter-export-snippet)
 		     (headline . org-koma-letter-headline)
@@ -734,9 +735,13 @@ a communication channel."
           (format "\\KOMAoption{backaddress}{%s}\n"
                   (if (plist-get info :with-backaddress) "true" "false")))
      ;; Place.
-     (and (funcall check-scope 'place)
-          (format "\\setkomavar{place}{%s}\n"
-                  (if (plist-get info :with-place) (plist-get info :place) "")))
+     (let ((with-place-set (funcall check-scope 'with-place))
+	   (place-set (funcall check-scope 'place)))
+       (and (or (and with-place-set place-set)
+		(and (eq scope 'buffer) (or with-place-set place-set)))
+	    (format "\\setkomavar{place}{%s}\n"
+		    (if (plist-get info :with-place) (plist-get info :place)
+		      ""))))
      ;; Folding marks.
      (and (funcall check-scope 'with-foldmarks)
           (let ((foldmarks (plist-get info :with-foldmarks)))