Findpeaks

* Fix for plot_persistence() that not always showed up

* Fix for removing verbose messages in case of mask
* Fix in case of using caerus
*

* verbosity messaging is now consistently encoded. Progress bar is only shown if verbose>=4. nothing is shown with verbose=0
* input parameter `params` changed into `params_caerus`
* bug fix for unicodebyte
* code refactoring
* docstrings with examples added for the filtering approaches
* pytests included in github pipeline

* added another import to fix bug in previous version

* changed the manner of imports
* Fixed warning
* some code cleaning

* added doi