* Additional unit tests and rationalisation for Financial Functions
* Providing a series of sample files for Financial functions
* Refactor the last of the existing Financial functions
* Some more unit tests with default assignments from null arguments
Co-authored-by: Adrien Crivelli <adrien.crivelli@gmail.com>
* Extract ACCRINT() and ACCRINTM() Financial functions into their own class
Implement additional validations, with additional unit tests
Add support for the new calculation method argument for ACCRINT()
* Additional tests for Amortization functions