Component configuration interfaces and XML-based implementations.

The `org.apache.avalon.framework.configuration` package contains primarily:

- The Configurable interface, which a Component implements if it needs to be configured with externally-specified data before it is initialized.
- The Configuration interface, an implementation of which will be passed to Components that implement Configurable.
- The Reconfigurable interface, which Components implement if they need to be reconfigured at runtime.
- Various classes providing the default XML-based implementation of Configuration. The mapping from XML to Configuration tree is described in DefaultConfigurationBuilder.