Release version 1.1.0

Release version 1.0.0

Release 0.4.0

Release 0.3.2

Throw if component's Lifecycle method returns nil

It is a common mistake for component Lifecycle methods (start and stop)
to return nil instead of the updated component instance. These archived
commits check for a returned nil when updating a system and throw an
exception. This prevents potential legitimate use cases for component
function returning nil.

Instead, commit fb89150 changes the error message when a component is
discovered to be nil in the system map. This error message points users
in the right direction without preventing a component from returning nil
if that's what it needs to do.

See #17 for further
discussion.

Release version 0.3.1

Version 0.3.0 release tag

Release 0.2.3

Release 0.2.2 on September 7, 2014

Release 0.2.1