Filter funcs

See merge request !256

Fixes for fuzzy tests

See merge request !258

if the history is altered manually (by a data proc function) newly inserted indexes and data must be
not masked and therefore must use `True` as default value for the mask. Otherwise nan's could be
propagate through the history. Hard to explain...

Fixed libtest

See merge request !255

Dios integration

Closes #188

See merge request !252

for bigger datasets.

Python 3.9 testing

See merge request !253

Update requirements and dependencies

See merge request !254

code formatting with black

Closes #185

See merge request !251

Drift correct generalisation

See merge request !238

Cleanup obsolete functions

Closes #176 and #187

See merge request !250

bump dependencies

See merge request !249

Fix the fuzzy tests

See merge request !239

API interface fixes

See merge request !236