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.
* First steps splitting out the Amortization and Deprecation Excel functions from Financials
* Verify which methods allow negative values for arguments
* Additional unit tests for SLN() and SYD()
* Additional unit tests for DDB()
* Additional unit tests for DB()
* Verify Amortization cases where salvage is greater than cost
* More unit tests for Amortization
* Resolve broken test in AMORLINC() and extract amortizationCoefficient calculation
* verify amortizationCoefficient calculation
* Extract YIELDDISC() and YIELDMAT() to Financial\Securities
* Additional validation for Securities Yield functions
Adrien Crivelli
Mark Baker