PrettyJSON: Implement 'series :: Char -> Char -> (a -> Doc) -> [a] -> Doc'

Implement 'series :: Char -> Char -> (a -> Doc) -> [a] -> Doc' and
'punctuate :: Doc -> [Doc] -> [Doc]'. Stub 'fsep :: [Doc] -> Doc'.
PrettyJSON: Finish implementing 'renderJValue :: JValue -> Doc'

Implement 'renderJValue :: JValue -> Doc' for 'JArray' and 'JObject'
parameters