LaTeX writer: Use \textquotesingle for ' in inline code.

Otherwise we get curly quotes in the PDF output.
Closes #1364.

src/Text/Pandoc/Writers/LaTeX.hs

@@ -220,6 +220,7 @@ stringToLaTeX  ctx (x:xs) = do
        '>' -> "\\textgreater{}" ++ rest
        '[' -> "{[}" ++ rest  -- to avoid interpretation as
        ']' -> "{]}" ++ rest  -- optional arguments
+       '\'' | ctx == CodeString -> "\\textquotesingle{}" ++ rest
        '\160' -> "~" ++ rest
        '\x2026' -> "\\ldots{}" ++ rest
        '\x2018' | ligatures -> "`" ++ rest

tests/Tests/Writers/LaTeX.hs

@@ -63,5 +63,7 @@ tests = [ testGroup "code blocks"
             strikeout (code "foo" <> space
               <> str "bar") =?>
             "\\sout{\\texttt{foo} bar}"
+          , "single quotes" =:
+              code "dog's" =?> "\\texttt{dog\\textquotesingle{}s}"
           ]
         ]