-------------------
- the methods `create_instances_from_lists` and `create_instances_from_matrices` of the
`weka.core.dataset` module can handle missing values now (`None` in case of lists,
`nan` in case of matrices), as well as being able to force columns to be nominal
- added the method `load_csv_file` to the module `weka.core.converters` to provide a more
reliable way of loading CSV files compared to Weka's native `CSVLoader` converter
(uses Python's csv module and then calls `create_instances_from_lists`).
- added `simple_range` library as dependency to make it easier to generate integer list from range strings
- added `weka.core.utils` module with following methods: correlation, variance, normalize
- updated requirements (and install instructions) to make pww3 work with Python 3.11+