While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
And quite a bit more manual changes. The idea is that typing of our
tests can be a bit more loose, so we assume PHPDoc is mostly correct. If
that happens to be wrong, it should be caught by the tests themselves.
Add unit tests to cover all of HashTable. I was hoping to do this without source changes, but this class does require a deep clone, and, as the new unit tests revealed, the existing code did not fill the bill - it cloned objects, but not arrays which contained objects, and all the object variables in this class are arrays which can contain objects.