Textdirectory

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* added filter_by_filenames
* added filter_by_filename_not_contains
* added transform_to_files
* added transformation_eebop4_to_plaintext
* added transformation_replace_digits
* added transformation_ftfy
* added fast and skip_checkpoint options to load_files
* added __repr__ method to TextDirectory
* added examples
* upgraded to spaCy 3
* improved the test suite
* fixed some minor bugs

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* added transformation_expand_english_contractions
* fixed some minor bugs
* added __str__ method to TextDirectory
* added filename to __str__ output
* added `get_text` method

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* added long_description_content_type to setup.py

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* added transformation_remove_weird_tokens
* added transformation_lemmatizer
* fixed some minor bugs
* added a function to revert applied filters
* added a function that prints the current pipeline
* added a function that clears all transformations
* added helper functions to list available filters and transformations
* fixed a bug in which ``tabulate_flat_list_of_dicts`` would fail if the dictionary was empty
* ``self.aggregation`` does not hold a copy of the files anymore but references to ``self.files``
* transformations relying on spaCy are now estimating a max_length based on available memory
* TextDirectory objects are now iterable

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* changed the data packaging

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* added transformation_remove_stopwords
* added transformation_remove_htmltags
* fixed some minor bugs