Release 3.1.0

[jcoliz]

Release 3.1.0

This has been posted to the NuGet Gallery. The issue remains open to track any problems or concerns that anyone may have.

Here's what's new:

This release closes all known issues and implements newer functions which were added to Excel since the library was originally releases.

• Adds PDURATION function. Returns the number of periods required by an investment to reach a specified value. (Resolves Implement PDURATION #62)
• Adds RRI function. Also used for CAGR. Returns an equivalent interest rate for the growth of an investment. (Resolves Implement CAGR/RRI #60)
• Improves XIRR function by reducing the precision required before an answer is returned. (Fixes Find Root operation does not follow Excel spec as stated in comment => common.fs #27)
• Improves ACCRINT function by allowing first interest date on the settlement date. (Fixes Behavior of AccrInt does not match Excel when firstInterest <= settlement #22)
• Adds PriceAllowNegativeYield function, which operates like the PRICE function except that it allows negative yield inputs. This is experimental. We'd love feedback on how this works for folks. (Fixes Can't calculate price with a negative yield #13)

[jcoliz]

Release 3.1.0 is out. This completes all work I have in mind for ExcelFinancialFunctions at the moment.

[jcoliz]

Superseded by Release 3.2.0 #68