Textile parser: Expanded list of stringBreakers.

This fixes a bug on input like "(_hello_)" which should
be a parenthesized emphasized "hello".

The new list is taken from the PHP source of textile 2.4.

src/Text/Pandoc/Readers/Textile.hs

@@ -434,7 +434,7 @@ markupChars = "\\*#_@~-+^|%=[]"
 --  punctuation. Double quote breaks for named links. > and < break
 --  for inline html.
 stringBreakers :: [Char]
-stringBreakers = " \t\n('-.,:!?;\"<>"
+stringBreakers = " \t\n\r.,\"'?!;:<>«»„“”‚‘’()[]"
 
 wordBoundaries :: [Char]
 wordBoundaries = markupChars ++ stringBreakers