Markdown reader: Fixed whitespace footnote bug (Jesse Rosenthal).

The problem was in input like this:

[^1]:  note

not in note.

Also added a test case for this.

src/Tests/Readers/Markdown.hs

@@ -26,4 +26,14 @@ tests = [ testGroup "inline code"
             "`*` {.haskell .special x=\"7\"}"
             =?> para (codeWith ("",["haskell","special"],[("x","7")]) "*")
           ]
+        , testGroup "footnotes"
+          [ "indent followed by newline" =: [_LIT|
+[^1]
+
+[^1]:  my note
+
+    
+not in note
+|]          =?> para (note (para "my note")) +++ para "not in note"
+          ]
         ]

src/Text/Pandoc/Readers/Markdown.hs

@@ -263,7 +263,8 @@ noteBlock = try $ do
   char ':'
   optional blankline
   optional indentSpaces
-  raw <- sepBy rawLines (try (blankline >> indentSpaces))
+  raw <- sepBy rawLines (try (blankline >> indentSpaces >> 
+                                        notFollowedBy newline))
   optional blanklines
   endPos <- getPosition
   let newnote = (ref, (intercalate "\n" raw) ++ "\n\n")