Derive Serialize, Deserialize for wrapper types

This crate provides several custom derives that make it more convenient to create implementations of serde's Serialize and Deserialize traits for types T that can be converted to or from another type S which already does implement those traits.

One use case is if you have a single-field type like

```rust

[derive(SerializeInto, DeserializeFrom)]

struct Contact { email: String, } ```

which you want to serialize and deserialize as a string instead of a struct.

Another example is a validated wrapper type like

```rust

[derive(DeserializeTryFrom)]

struct Email(String); ```

that should never be instantianted with a string that doesn't represent a valid email address. If you implement Email: TryFrom<String> using the try_from crate, such that conversion fails for invalid addresses, the derived Deserialize will also fail if the string is in the wrong format.