Add a pre-commit configuration

[QuLogic]

PR Summary

As in Matplotlib, it tests flake8, codespell, and some whitespace. It also checks YAML linting and the YAML schema.

Also, add an ignored word for codespell, and a schema for checking package YAML files. The latter confirms that:

• all required keys are included
• values are the right type, such as keywords being an array, not a string
• the description ends with a period

[QuLogic]

Seems that we probably need to merge the config before pre-commit will run.

[timhoffm]

Let's try this.