Updating `DMCSimulationResults.__init__`.

Storing the number of taxon pairs and the number of simulation reps as
attributes. Updating test data and tests accordingly.
Adding functions to `utils.functions` module.

Adding `get_new_path` and `get_sublist_greater_than` functions.
Adding associated tests to `test_util_functions.py`.
Updating `DMCSimulationResults` class.

Adding the optional parsing of tau exclusion information in the
`flat_result_iter` and `write_result_summaries` methods.