TargetedEventInterface should should also ensure the EventInterface is fulfilled.
TargetedEvent now ensures the interface is implemented.

PHP does not allow traits to implement interfaces.
Adding EventTrait, containing an implementation of EventInterface.

Event class updated to utilise this new trait.
Correcting PHPDoc @link tags.

The annotations were pointing to the wrong repository.
Merge pull request #7 from nick-jones/fix.phpdoc.links

Correct PHPDoc @link tags
Merge pull request #6 from nick-jones/fix.targeted.events

Moving TargetedEventInterface implementation from trait into TargetedEvent class