Split general methods from country-specific methods

[rubencalje]

Right now NLmod contains general methods (resampling, Dataset-methods) and methods specifically for the Netherlands.

The general methods can be used by people outside the Netherlands, possibly from other Python-packages. At the IAH in Davos in 2024, Belgian geohydrologists mentioned it would be a cool idea to make a BEmod (or Bmod?). It would be great if NLmod and BEmod would share the same general methods, so bugfixes and improvements are automatically available to both. Models at the border of the Netherlands and Belgium could then use both NLmod and BEmod to combine the country-specific datasets.

Therefore, this discussion is started, so we can discuss the way to separate general methods from country-specific methods. Feel free to share your ideas!