Add a method to specify the type of processor.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Make processors register themselves automatically.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Load processors from the ProcessorRegistry.

This allows users to simply specify a list of paths in the configuration
file and have all of them loaded automatically.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Implement saving of metadata after processing.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Implement delayed loading of messages.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>