Pastastore

Minor update
- remove pandas max dependency
- minor fixes, see 45

Major internal refactoring of code, moved all general code to BaseConnector class, all specific code kept in specific Connector classes.

Add features:
- add update methods for timeseries (for adding new data)
- add some basic support for adding pastas.TimeSeries
- add copy_database function
- add plot and map methods (see [notebook](https://pastastore.readthedocs.io/en/latest/examples/003_pastastore_plots_and_maps.html))
- add rudimentary search timeseries method (for lazy people who only want to see metadata but only type the first few letters)
- add option to check whether timeseries in a pastas.Model are exactly the same as in the store (see `PastaStore.set_check_model_series_values()`, by default off)
- minor(bug)fixes and improvements

Improvements and fixes:

- improve support for RechargeModel
- automatic updating of tmin/tmax in timeseries settings and models
- add option to retrieve metadata in `pstore.get_oseries()` and `pstore.get_stresses()`
- improve `get_oseries_distances` to exclude self
- improve reading database from zipfiles
- add option to pass name for added RechargeModel

- Add PasConnector object for storing timeseries and models as Pastas .pas-files on disk. Simplest method to store pastas data on disk without any external dependencies (only pastastore and pastas required).
- Add method for detailed comparison of pastas Models: pastastore.util.compare_models()
- Add method to export all timeseries in a model as CSV-files.
- Add support for models using RechargeModel
- Add benchmarks
- Bug fixes:
- Improve reading/writing zipfiles
- Check for unsupported characters in metadata dictionaries
- and more...

Minor update:

- new maxdist argument for PastaStore.get_nearest
- allow multiple entries for kind keyword argument in PastaStore methods
- improve messaging when linking to existing databases
- add names="all" as option to get all series/stresses/models
- add methods in utils for emptying databases, improve method for deleting databases
- fix for getting nearest stresses when x, y coordinates are NaN
- some improvements in documentation