* Additional unit tests for VLOOKUP() and HLOOKUP()
* Additional unit tests for CHOOSE()
* Unit tests for HYPERLINK() function
* Fix CHOOSE() test for spillage
* 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