• Support autocompletion for the most commonly used args/kwargs of the top level API and remove some arg duplication. Couldn't get this done for everything and for all args/kwargs, but it should be an improvement compared to now. Step by step.
• Also added Span and Transaction to the docs. (For some reason, autodocumenting the tracing.py module doesn't do anything so had to add the classes explicitly.)
• Expanded some docstrings, too.

Fixes #2199
Fixes #2196