Changed format of --list-extensions.

Now the + or - occurs first.

MANUAL.txt

@@ -389,9 +389,10 @@ General options
 
 `--list-extensions`[`=`*FORMAT*]
 
-:   List supported Markdown extensions, one per line, followed
+:   List supported Markdown extensions, one per line, preceded
     by a `+` or `-` indicating whether it is enabled by default
-    in *FORMAT* (defaulting to pandoc's Markdown).
+    in *FORMAT*. If *FORMAT* is not specified, defaults for
+    pandoc's Markdown are given.
 
 `--list-highlight-languages`
 

src/Text/Pandoc/App.hs

@@ -1592,10 +1592,9 @@ options =
                  (OptArg
                   (\arg _ -> do
                      let exts = getDefaultExtensions (fromMaybe "markdown" arg)
-                     let showExt x = drop 4 (show x) ++
-                                       if extensionEnabled x exts
-                                          then " +"
-                                          else " -"
+                     let showExt x = (if extensionEnabled x exts
+                                         then '+'
+                                         else '-') : drop 4 (show x)
                      mapM_ (UTF8.hPutStrLn stdout . showExt)
                                ([minBound..maxBound] :: [Extension])
                      exitSuccess )