* 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
* 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()
Mark Baker
Adrien Crivelli