Description

• adds session-scoped fixtures to tests and uses them where possible throughout unit test suite
• adds an actual quickstart to the docs, and moves the old quickstart to a slightly updated "walkthrough"
• improves some documentation in the code

Motivation and Context

This improves maintainability (and performance?) of the testing suite, which means less hassle for me. It also fixes some issues with the walkthrough (out-of-date code and now-irrelevant notes), and adds a proper quickstart, so new users have a better introduction to the package's functionality.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation, and I have updated it accordingly.