v0.5.0

A major feature release with a significant API improvement!

This update does not involve any BC breaks, but we figured the new API provides
significant features that warrant a major version bump. Existing code will
continue to work without changes, but you're highly recommended to consider
using the new lazy connections as detailed below.

• Feature: Add new createLazyConnection() method to only connect on demand and
  implement "idle" timeout to close underlying connection when unused.
  (#87 and #88 by @clue)

  // new
  $connection = $factory->createLazyConnection($url);
  $connection->query(…);

  This method immediately returns a "virtual" connection implementing the
  ConnectionInterface that can be used to
  interface with your MySQL database. Internally, it lazily creates the
  underlying database connection only on demand once the first request is
  invoked on this instance and will queue all outstanding requests until
  the underlying connection is ready. Additionally, it will only keep this
  underlying connection in an "idle" state for 60s by default and will
  automatically end the underlying connection when it is no longer needed.

  From a consumer side this means that you can start sending queries to the
  database right away while the underlying connection may still be
  outstanding. Because creating this underlying connection may take some
  time, it will enqueue all oustanding commands and will ensure that all
  commands will be executed in correct order once the connection is ready.
  In other words, this "virtual" connection behaves just like a "real"
  connection as described in the ConnectionInterface and frees you from
  having to deal with its async resolution.

• Feature: Support connection timeouts.
  (#86 by @clue)