v2.0.0

This release reworks the interface of the schulze-condorcet package and makes it more accessible.

• schulze_evaluate provides a single vote string, reflecting the overall preference
• schulze_evaluate_detailed provides more insights in the preference by revealing the pro and contra votes for each candidate in the result
• pairwise_preference gives a direct compairson between each candidate over their preference.

Additonally, the type hints of the different representations of votes (either as strings or as tuple of tuples / list of lists) are more specific now, and some convenient functions are added in util.py to convert the different representations of votes into each other.