Add API interface

Make it easier to retrieve metadata from the publicdb using its API
Takes the urllib/json stuff out of your hands
Fix init docstrings
Add the offending url to the exception
Add docstrings to API functions
Add API module to docs

Include example usage of the class
Combine param names to prevent it being seen as param type
Rename id to number for clarity
Add nested network function

Also fix typo in a function name
Add tests for API module
Add extra test conditions for num events
Use _number instead of _id, as is done in the publicdb API
Update format of scintillators in API

Add test for n detectors
Add support for date in station_info

Also support date for the detectors of a station
Add support for getting event traces (with test ✨)
Merge branch 'api'

Add support for the publicdb API to retrieve HiSPARC metadata