Give injection provider more informations about requested injection

[mikey]

I would like to have more information available inside an injection provider to allow the provider to decide which implementation (or concrete instance) to return. Consider the following:

$binder->bind('stubDatabaseConnection')->named('downloads')->toProvider(new DatabaseConnectionProvider('downloads'));
$binder->bind('stubDatabaseConnection')->named('press')->toProvider(new DatabaseConnectionProvider('press'));
$binder->bind('stubDatabaseConnection')->named('jobs')->toProvider(new DatabaseConnectionProvider('jobs'));

In this example you need several provider instances, one for each named injection. If the provider would know itself about the named annotation it could decide itself what to return. This would keep the amount of bindings lower, and one would only need one provider instance instead of several ones.

[mikey]

Some thoughts for the refactoring:

- Scopes and bindings only return injection providers instead of concrete instances to inject. - Injector gets instance from injection provider, which in turn it gets from the binding.

[mikey]

Implemented with r1370.

Todo: Increase test coverage, not all use cases are covered. Todo: Update documentation.

[mikey]

Test cases added with r1371, documentation was updated as well.