Tracker for deprecated stuff

[niknetniko]

This issue can track deprecated stuff we still support, which we can remove if there are no more known users.

• [ ] deprecated field runs in the test suites
• [ ] plan.json as default for test suite names in the config
• [ ] deprecated names testplan and plan_name in the config (for test_suite)
• [ ] deprecated field evaluators (for functions)
• [ ] deprecated fields evaluator (for oracle)
• [ ] ignored field essential
• [ ] ignored field show_expected
• [ ] statements can have return values in the DSL
• [x] return_raw