* Merge branch 'master' of C:\Projects\PHPOffice\PHPSpreadsheet\develop with conflicts.
* More statistical tests
* Further statistical tests
* Unit tests for some of the trend functions
* resolve scrutiniser objections
* Fix order of @return types :-(
* Merge branch 'master' of C:\Projects\PHPOffice\PHPSpreadsheet\develop with conflicts.
* Additional unit tests for average functions, and fix to AVERAGEIF() function if third argument is passed
* Update change log
* Stricter typed comparisons in AVERAGEIF() conditions
* Unit tests for BETADIST() and BETAINV()