Lazy loading

The main feature of this minor release is the lazy loader. Use the setLoader() method of the Container class to pass a callback that constructs your dependency, rather than having to have a pre-constructed object when using the set() method.

An often overlooked benefit of using service containers is the fact that, as the framework knows when and where a service is being requested, it doesn't actually need to construct the object until the first time it's requested.

A good example of where this will benefit is the Database. Using a lazy-loaded service container has two implementation benefits:

1. On pages that don't query the database, the database object is never constructed, so no connections are made to the database until they're used.
2. The framework can suggest default behaviour for the construction of objects, but if the developer wants to use a different implementation of the same interface, they are free to override it.

The other benefit is how the container is used: the developer can register their own classes in the container, again only being constructed at use-time, allowing much richer abstraction patterns like the Repository Pattern hiding any database implementations.