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 refactoring the Lookup and Reference functions
- COLUMN(), COLUMNS(), ROW() and ROWS()
- LOOKUP(), VLOOKUP() and HLOOKUP()
- Refactor TRANSPOSE() and ADDRESS() functions into their own classes
* Additional unit tests
- LOOKUP()
- TRANSPOSE()
- ADDRESS()
* Highlight VLOOKUP bug with a new test
* Remove useless statements + fix VLOOKUP bug
Please not that we have still inconsistencies in Excel (See LOOKUP and
VLOOKUP.php test files)
* Base strtolower on our StringHelper in LookupRef