Target Normalizers

A target normalizer is used to normalize targets to make them usable for training. Some examples of normalization steps are replacing unknown characters with a fixed label or making everyting lower case. A target normalizer can be different for each database. To create a new target normalizer you should create a file with normalize method that takes a transcription and an alphabet as input and returns the normalized transcription. You should then add it to the factory method in normalizer_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.