Org writer: remove blank line after figure caption

Org-mode only treats an image as a figure if it is directly preceded by
a caption.

src/Text/Pandoc/Writers/Org.hs

@@ -158,10 +158,9 @@ blockToOrg (Plain inlines) = inlineListToOrg inlines
 blockToOrg (Para [Image attr txt (src,'f':'i':'g':':':tit)]) = do
   capt <- if null txt
              then return empty
-             else (\c -> "#+CAPTION: " <> c <> blankline) `fmap`
-                    inlineListToOrg txt
+             else ("#+CAPTION: " <>) `fmap` inlineListToOrg txt
   img <- inlineToOrg (Image attr txt (src,tit))
-  return $ capt <> img
+  return $ capt $$ img
 blockToOrg (Para inlines) = do
   contents <- inlineListToOrg inlines
   return $ contents <> blankline

tests/writer.org

@@ -808,7 +808,6 @@ Auto-links should not occur here: =<http://example.com/>=
 From "Voyage dans la Lune" by Georges Melies (1902):
 
 #+CAPTION: lalune
-
 [[lalune.jpg]]
 Here is a movie [[movie.jpg]] icon.