LaTeX reader: Parse {groups} as Span.

This is needed for accurate conversion of bibtex titles,
since we need to know what was protected from titlecase conversions.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -176,7 +176,7 @@ inline = (mempty <$ comment)
      <|> (space  <$ sp)
      <|> inlineText
      <|> inlineCommand
-     <|> grouped inline
+     <|> inlineGroup
      <|> (char '-' *> option (str "-")
            ((char '-') *> option (str "–") (str "—" <$ char '-')))
      <|> double_quote
@@ -199,6 +199,15 @@ inline = (mempty <$ comment)
 inlines :: LP Inlines
 inlines = mconcat <$> many (notFollowedBy (char '}') *> inline)
 
+inlineGroup :: LP Inlines
+inlineGroup = do
+  ils <- grouped inline
+  if isNull ils
+     then return mempty
+     else return $ spanWith nullAttr ils
+          -- we need the span so we can detitlecase bibtex entries;
+          -- we need to know when something is {C}apitalized
+
 block :: LP Blocks
 block = (mempty <$ comment)
     <|> (mempty <$ ((spaceChar <|> newline) *> spaces))