Merge tag '0.6' into develop

- Improved typing support:
        - Fixes wrong types in u_distance_stats_sqr.
        - Add missing types in rowwise.
- Improve the documentation:
        - New documentation theme.
        - Added links in the theory.
        - Added examples to the documentation.
- Performance improvements:
        - Improve the computation time of distances for Numpy arrays, which improves performance for energy distance and the naive case of distance covariance/correlation.
        - Improve AVL algorithm for distance covariance performance to bring it closer to mergesort.
        - Refactor distance covariance to be able to compute distance correlation without additional calls to the covariance function.

dcor/VERSION

@@ -1 +1 @@
-0.5.7
+0.6