LaTeX reader: be more forgiving of non-standard characters.

E.g. `^` outside of math.  Some custom environments give
these a meaning, so we should try not to fall over when we
encounter them.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -232,7 +232,7 @@ inline = (mempty <$ comment)
      <|> (guardEnabled Ext_literate_haskell *> char '|' *> doLHSverb)
      <|> (str . (:[]) <$> tildeEscape)
      <|> (str . (:[]) <$> oneOf "[]")
-     <|> (str . (:[]) <$> oneOf "#&") -- TODO print warning?
+     <|> (str . (:[]) <$> oneOf "#&~^'`\"[]") -- TODO print warning?
      -- <|> (str <$> count 1 (satisfy (\c -> c /= '\\' && c /='\n' && c /='}' && c /='{'))) -- eat random leftover characters
 
 inlines :: LP Inlines