Evaluator
 - main() method splits the given corpus in the folder "brown_learn" into a training and a evaluation corpus (10:1), trains over the training corpus und tags the eval corpus. Then the FMeasure is calculated.  This is done 10 times and to calculate the mean and median of the FMeasures.
POSTagging
 - this class provides the functionality asked by Philippe: call the main class with the arguments "train <directory_name>" to train a model, wich is written to "model". Using the arguments "annotate <directory_name>" tags all sentences in the files of the given directory and writes them back to the "<old_filename>.pos"