LaTeX reader: Made rawLaTeXInline more flexible.

Now it will also try to parse block commands.  This is usually
what we want, given how rawLaTeXInline is used in the markdown
and textile readers.  If a block-level LaTeX command is used
in the middle of a paragraph (e.g. `\subtitle` inside a title),
we can treat it as raw inline LaTeX.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -717,10 +717,8 @@ rawLaTeXBlock = snd <$> try (withRaw (environment <|> blockCommand))
 
 rawLaTeXInline :: Parser [Char] ParserState Inline
 rawLaTeXInline = do
-  (res, raw) <- withRaw inlineCommand
-  if res == mempty
-     then return (Str "")
-     else RawInline "latex" <$> (applyMacros' raw)
+  raw <- (snd <$> withRaw inlineCommand) <|> (snd <$> withRaw blockCommand)
+  RawInline "latex" <$> applyMacros' raw
 
 environments :: M.Map String (LP Blocks)
 environments = M.fromList