Update Reader/WriterEntityFactory

Add `WriterEntityFactory::createWriterFromFile`, working like `ReaderEntityFactory::createReaderFromFile` (guessing writer type from file name).
Use static functions when needed.

src/Spout/Reader/Common/Creator/ReaderEntityFactory.php

@@ -13,25 +13,25 @@ class ReaderEntityFactory
     /**
      * This creates an instance of the appropriate reader, given the type of the file to be read
      *
-     * @param  string $readerType Type of the reader to instantiate
+     * @param string $readerType Type of the reader to instantiate
      * @throws \Box\Spout\Common\Exception\UnsupportedTypeException
      * @return ReaderInterface
      */
     public static function createReader($readerType)
     {
-        return (new ReaderFactory())->create($readerType);
+        return ReaderFactory::create($readerType);
     }
 
     /**
      * Creates a reader by file extension
      *
-     * @param string The path to the spreadsheet file. Supported extensions are .csv,.ods and .xlsx
+     * @param string $path The path to the spreadsheet file. Supported extensions are .csv, .ods and .xlsx
      * @throws \Box\Spout\Common\Exception\IOException
      * @throws \Box\Spout\Common\Exception\UnsupportedTypeException
      * @return ReaderInterface
      */
     public static function createReaderFromFile(string $path)
     {
-        return (new ReaderFactory())->createFromFile($path);
+        return ReaderFactory::createFromFile($path);
     }
 }