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.
* Start work on array-enabling the Lookup and Reference functions
Requires a new method (`evaluateArrayArgumentsSubsetFrom()`) in the `ArrayEnabled` Trait to handle functions where the arguments that need special array handling are trailing rather than leading arguments
* Extract LookupRef\INDEX() into index() method of LookupRef\Matrix class
Additional tests
* Bugfix for returning a column using INDEX()
* Some improvements to ROW() and COLUMN()
* Simplify some of the INDEX() logic, eliminating redundant code
Adrien Crivelli
Mark Baker
Maxim