This changes the API in various ways, and updates the backends for this.
Overall, this is a massive simplification of the API, as most future backends
can't support the previously-offered API.
This also removes the testautomation pen code (not only did these interfaces
change completely, it also did something no other test did: mock the internal
API), and replaces testpen.c with a different implementation (the existing
code was fine, it was just easier to start from scratch than update it).
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