Merge branch 'master' of github.com:box/spout into add-phpstan

 Conflicts:

	.travis.yml

	CONTRIBUTING.md

	composer.json

	src/Spout/Common/Entity/Cell.php

	tests/Spout/Writer/ODS/WriterTest.php

tests/Spout/Writer/XLSX/WriterWithStyleTest.php

@@ -32,7 +32,7 @@ class WriterWithStyleTest extends TestCase
     /**
      * @return void
      */
-    public function setUp()
+    public function setUp() : void
     {
         $this->defaultStyle = (new StyleBuilder())->build();
     }