Hydropandas

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- remove fieldlogger functions as they are outdated and unused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.

Most fixes were already added to the previous release (0.3.3). This release was obfuscated by the attempt to automate PyPi release via github actions. Therefore a full overview of this (0.3.4) and previous (0.3.3) updates:

- The Dino WSDL API is down. For now the functions related to this API remain in the Hydropandas package but will throw an error. All the tests that use this API are moved to the file 'no_test_dino_wsdl.py'. In time we might remove the tests and function related to the WSDL API. This is related to 56.
- The KNMI function is updated to get the latest measurements even if there are no measurements at the Bilt for over a month. This is related to 54.
- The automated PyPi release after publishing updates like this seems to work now.