Row objects and Cell styling

This commit introduces Row and Cell entities, that will replace the arrays passed in previously.
It also adds support for Cell styling (instead of Row styling only).

src/Spout/Writer/Common/Manager/Style/StyleManagerInterface.php

@@ -2,6 +2,7 @@
 
 namespace Box\Spout\Writer\Common\Manager\Style;
 
+use Box\Spout\Writer\Common\Entity\Cell;
 use Box\Spout\Writer\Common\Entity\Style\Style;
 
 /**
@@ -22,9 +23,8 @@ interface StyleManagerInterface
      * Apply additional styles if the given row needs it.
      * Typically, set "wrap text" if a cell contains a new line.
      *
-     * @param Style $style The original style
-     * @param array $dataRow The row the style will be applied to
+     * @param Cell $cell
      * @return Style The updated style
      */
-    public function applyExtraStylesIfNeeded($style, $dataRow);
+    public function applyExtraStylesIfNeeded(Cell $cell);
 }