* Merge branch 'master' of C:\Projects\PHPOffice\PHPSpreadsheet\develop with conflicts.
* New statistical tests
* Sniffs
* Additional statistical function unit tests
* Additional statistical function unit tests
* Fix case-sensitivity
* Fix HARMEAN code logic
* Unit tests refactored into individual files for all logical functions
Implemented IFNA()
* Fix silly typo
* NOT needs ...args to allow for test when no argument passed
* Codestyle
* Use instance asserts
- Fix ISFORMULA() function to work with a cell reference to another worksheet
- Added calculation engine support for the new functions that were added in MS Excel 2013 and MS Excel 2016
- Text Functions
- CONCAT() Synonym for CONCATENATE()
- NUMBERVALUE() Converts text to a number, in a locale-independent way
- UNICHAR() Synonym for CHAR() in PHPSpreadsheet, which has always used UTF-8 internally
- UNIORD() Synonym for ORD() in PHPSpreadsheet, which has always used UTF-8 internally
- TEXTJOIN() Joins together two or more text strings, separated by a delimiter
- Logical Functions
- XOR() Returns a logical Exclusive Or of all arguments
- Date/Time Functions
- ISOWEEKNUM() Returns the ISO 8601 week number of the year for a given date
- Lookup and Reference Functions
- FORMULATEXT() Returns a formula as a string
- Engineering Functions
- ERF.PRECISE() Returns the error function integrated between 0 and a supplied limit
- ERFC.PRECISE() Synonym for ERFC
- Math and Trig Functions
- SEC() Returns the secant of an angle
- SECH() Returns the hyperbolic secant of an angle
- CSC() Returns the cosecant of an angle
- CSCH() Returns the hyperbolic cosecant of an angle
- COT() Returns the cotangent of an angle
- COTH() Returns the hyperbolic cotangent of an angle
- ACOT() Returns the cotangent of an angle
- ACOTH() Returns the hyperbolic cotangent of an angle
- Financial Functions
- PDURATION() Calculates the number of periods required for an investment to reach a specified value
- RRI() Calculates the interest rate required for an investment to grow to a specified future value
Dawid Warmuz