Trainers

A trainer is used to update the model parameters to minimize some loss function. To create a new trainer you should inherit from the general Trainer class defined in trainer.py and overwrite the abstract methods. Afterwards yo should add the trainer to the factory method in trainer_factory.py. It is also very helpful to create a default configuration in the defaults directory. The name of the file should be the name of the class in lower case with the .cfg extension.