v0.9.8

• Implement serde::Deserializer for &serde_json::Value (#261)

  This can be convenient for deserializing from indexed content:

  let v = json!({ "m": { "serde": 1, "json": 100 } });
  
  let m: BTreeMap<String, u8> = Deserialize::deserialize(&v["m"])?;

• Add an entry API to the serde_json::Map type, just like what BTreeMap has (#236)

  let mut map = serde_json::Map::new();
  
  map.entry("serde").or_insert(json!(12));
  
  match map.entry("serde") {
      Entry::Vacant(vacant) => {
          // can insert
      }
      Entry::Occupied(occupied) => {
          // can read, mutate, remove
      }
  }
  
  assert_eq!(map["serde"], 12);

• Quit using voldemort types to parameterize the deserializer; this should make storing serde_json::Deserializer and StreamDeserializer in structs more convenient (#260)