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.
Fix#2389. Hyperlinks referring to cells in the spreadsheet itself are not being handled properly. This is the first namespacing regression identified for release 19. Usual cause and fix - need to take greater care with attributes than was previously the case.