* required_if checks should have three or four parts.
* Validate mutually_exclusive, required_together, required_one_of, required_if and required_by.
* Simplify code.
* Improve messages.
* Add changelog.
* Sanity check.
* Update docs.
* Update ignore.txt.
* Don't continue with tests when terms are not strings.
* Remove ignore.txt entry.
* Make sure validate-modules doesn't choke on things already flagged by schema test.
* Check required_if requirements list for strings.
