Hydropandas

Some small improvements:
- Remove pandas max dependency
- improve examples
- add interpolation to from_modflow method
- improve interpolation
- fix deprecation warning pyproj
- allow getting modellayer for piezometers from xarray DataSet

Minor improvements and fixes for the name of KNMI observations and the plotting module. Also some improvements to the testing.

This update includes:
- reinstate and update the old KNMI api functions
- create a __repr__ for observation objects
- replace verbose with the logging module
- remove fieldlogger functions as they are outdated and unused
- many smaller fixes and documentation improvements

Main fix for the KNMI api that went offline see 59.

Other minor fixes:
- add option for unstructured grids in io_modflow
- fix error with duplicate index in Dino, 61
- fix memory usage of io_fews and add filtering on xml headers

Minor fixes
- fix `io_xml` import error
- update meteo stations coordinates
- add overwrite keyword argument to `to_pastastore()`

When testing the github actions for PyPi releases I created a few releases (0.3.3, 0.3.4 and 0.3.3.0). Github actions will only succeed in creating a PyPi release when the new github release has a new version number. Since I tried to do a github release of 0.3.4 twice, the github action for creating the PyPi release is not working. Therefore this github release is only there to create a new PyPi release. From now on the PyPi release will work via github actions.