Release 0.3.0

* Added opt-in serde support to facilitate session and ack management (storing subscriptions and
  pids to disk or database). The actual encode()/decode() APIs are unchanged.
* Upgrated bytes dependency to 0.5. This brings growable buffers and a nicer API, [amongst other
  things](https://github.com/tokio-rs/bytes/blob/master/CHANGELOG.md).
* Implemented `Default for Pid`, `From<u16> for Pid`, and `TryFrom<Pid> for u16`. The `try_from()`
  method already existed but now comes from the `std::convert::TryFrom` trait.
* `encode()` now takes anything that implements the `BufMut` trait, not just a `ByteMut` struct. For
  technical reasons, `decode()` still takes `BytesMut`.
* Added option to opt-out of std library, allowing usage in `#[no_std]` projects, at the only cost
  of giving up the `Error` trait from std as well as `std::io` integration.

* Fix off-by one error when adding to a Pid wraps over.

* The minimum rust version is now 1.39.
* Improved `Pid` docs.

CHANGELOG.md

@@ -1,4 +1,4 @@
-# 0.3 (unreleased)
+# 0.3 (2020-03-23)
 
 ## API changes
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mqttrs"
-version = "0.2.0"
+version = "0.3.0"
 authors = ["00imvj00 <[email protected]>",
            "Vincent de Phily <[email protected]>",
            "Mathias Koch <[email protected]>"]

README.md

@@ -16,7 +16,7 @@ packet).
 
 ## Usage
 
-Add `mqttrs = "0.2"` and `bytes = "0.5"` to your `Cargo.toml`.
+Add `mqttrs = "0.3"` and `bytes = "0.5"` to your `Cargo.toml`.
 
 ```rust
 use mqttrs::*;
@@ -49,7 +49,7 @@ assert_eq!(Err(Error::InvalidHeader), decode(&mut garbage));
 
 ## Optional [serde](https://serde.rs/) support.
 
-Use  `mqttrs = { version = "0.2", features = [ "derive" ] }` in your `Cargo.toml`.
+Use  `mqttrs = { version = "0.3", features = [ "derive" ] }` in your `Cargo.toml`.
 
 Enabling this features adds `#[derive(Deserialize, Serialize)]` to some `mqttrs` types. This
 simplifies storing those structs in a database or file, typically to implement session support (qos,
@@ -60,7 +60,7 @@ functions.
 
 ## Optional `#[no_std]` support.
 
-Use `mqttrs = { version = "0.2", default-features = false }` in your `Cargo.toml` to remove the
+Use `mqttrs = { version = "0.3", default-features = false }` in your `Cargo.toml` to remove the
 default `std` feature.
 
 Disabling this feature comes with the cost of not implementing the `std::error::Error` trait,