Support COUNTIFS multiple arguments

Because Excel COUNTIFS function can have more than 2 arguments.

Closes #830

CHANGELOG.md

@@ -17,7 +17,8 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Improve XLSX parsing speed if no readFilter is applied - [#772](https://github.com/PHPOffice/PhpSpreadsheet/issues/772)
 - Fix column names if read filter calls in XLSX reader skip columns - [#777](https://github.com/PHPOffice/PhpSpreadsheet/pull/777)
 - Fix LOOKUP function which was breaking on edge cases - [#796](https://github.com/PHPOffice/PhpSpreadsheet/issues/796)
-- Fix VLOOKUP with exact matches
+- Fix VLOOKUP with exact matches - [#809](https://github.com/PHPOffice/PhpSpreadsheet/pull/809)
+- Support COUNTIFS multiple arguments - [#830](https://github.com/PHPOffice/PhpSpreadsheet/pull/830)
 
 ## [1.5.2] - 2018-11-25
 

src/PhpSpreadsheet/Calculation/Calculation.php

@@ -528,7 +528,7 @@ class Calculation
         'COUNTIFS' => [
             'category' => Category::CATEGORY_STATISTICAL,
             'functionCall' => [Functions::class, 'DUMMY'],
-            'argumentCount' => '2',
+            'argumentCount' => '2+',
         ],
         'COUPDAYBS' => [
             'category' => Category::CATEGORY_FINANCIAL,