Modified corpus_reader.py. Now it has train_sent_tokenizer() function to train the sentence tokenizer on the raw corpus, and pickle/save the resulting trained sentence tokenizer to disk. También, ahora la función load() carga este pickled sentence tokenizer, lo que aumenta considerablemente el tiempo de carga ya que no hay que entrenar el sentence tokenizer cada vez que cargamos el corpus. Aparte de eso ordené un poco ese script y agregué muchos comentarios. Files biblio.txt and todo.txt were also added to project root, as well as a placeholder README file in corpus/joint/, which can be viewed with the .readme() method of the corpus class instance.