ExcelFinancialFunctions

This release adds a small improvement: The library is now a strong-named assembly.

• Adds strong name assembly signing. (PR #69)

This release adds a small improvement to allowable function inputs.

• Removes needless constraint on 0-value inputs to FV & PMT functions. (PR #67)

• Adds PDURATION function. Returns the number of periods required by an investment to reach a specified value. (Resolves #62)
• Adds RRI function. Also used for CAGR. Returns an equivalent interest rate for the growth of an investment. (Resolves #60)
• Improves XIRR function by reducing the precision required before an answer is returned. (Fixes #27)
• Improves ACCRINT function by allowing first interest date on the settlement date. (Fixes #22)
• Adds PriceAllowNegativeYield function. This operates like the PRICE function except that it allows negative yield inputs. It is experimental. We'd love feedback on how this works for folks. (Fixes #13)

Retarget library onto .NET Standard 2.0.

• Adds explicit support for .NET Core 2.0 and higher including 5.0 and 6.0
• Removes support for full .NET Framework 4.6 and lower