GridHelper docs and sensible defaults updated

docs/api/extras/helpers/GridHelper.html

@@ -30,8 +30,8 @@
 
 		<h3>[name]( [page:number size], [page:Number divisions], [page:Color colorCenterLine], [page:Color colorGrid] )</h3>
 		<div>
-		size -- The size of the grid <br />
-		divisions -- The number of divisions across the grid <br />
+		size -- The size of the grid. Default is 10. <br />
+		divisions -- The number of divisions across the grid. Default is 10. <br />
 		colorCenterLine -- The color of the centerline. This can be a [page:Color], a hexadecimal value and an CSS-Color name. Default is 0x444444 <br />
 		colorGrid -- The color of the lines of the grid. This can be a [page:Color], a hexadecimal value and an CSS-Color name. Default is 0x888888
 		</div>

src/extras/helpers/GridHelper.js

@@ -11,7 +11,8 @@ import { Color } from '../../math/Color';
 
 function GridHelper( size, divisions, color1, color2 ) {
 
-	divisions = divisions || 1;
+	size = size || 10;
+	divisions = divisions || 10;
 	color1 = new Color( color1 !== undefined ? color1 : 0x444444 );
 	color2 = new Color( color2 !== undefined ? color2 : 0x888888 );