Rename Factory folder to Creator (#430)

src/Spout/Writer/Creator/InternalFactoryInterface.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Box\Spout\Writer\Creator;
+
+use Box\Spout\Writer\Manager\OptionsManagerInterface;
+use Box\Spout\Writer\Manager\WorkbookManagerInterface;
+
+/**
+ * Interface GeneralFactoryInterface
+ *
+ * @package Box\Spout\Writer\Creator
+ */
+interface InternalFactoryInterface
+{
+    /**
+     * @param OptionsManagerInterface $optionsManager
+     * @return WorkbookManagerInterface
+     */
+    public function createWorkbookManager(OptionsManagerInterface $optionsManager);
+}