Move Cell and Options to Entity folder (#429)

tests/Spout/Writer/ODS/WriterTest.php

@@ -6,8 +6,8 @@ use Box\Spout\Common\Exception\SpoutException;
 use Box\Spout\Common\Type;
 use Box\Spout\Reader\Wrapper\XMLReader;
 use Box\Spout\TestUsingResource;
-use Box\Spout\Writer\Common\Cell;
 use Box\Spout\Writer\Common\Helper\ZipHelper;
+use Box\Spout\Writer\Entity\Cell;
 use Box\Spout\Writer\WriterFactory;
 
 /**