adding stationarity score (lowe value r-> stationary signal) as the algorithm wasnt able to handle instationary signals

there might be an instationary error and a stationary error. we can work with the instationary error, because we are minmax normalizing the series in the beginning. the series might start at 1 and goes to 0 or the other way round - it makes sense to allow a small instationary error which is controllable with a minmax normalized series

- code cleanup and refactorizations
- simplifying cascade_case

alphashape parameter improvement

This reverts commit 7ba0059e.