Fix includeBlankOption with value 0 - issue 1022

Fix includeBlankOption with value 0 - issue contao#1022

implement contao#1022 (comment) with cast option values to string if values int - see https://github.com/menatwork/contao-multicolumnwizard-bundle/issues/63

core-bundle/src/Resources/contao/library/Contao/Widget.php

@@ -1155,7 +1155,7 @@ public static function optionSelected($strOption, $varValues)
 			return '';
 		}
 
-		return (\is_array($varValues) ? \in_array($strOption, $varValues) : $strOption == $varValues) ? ' selected' : '';
+		return \in_array((string) $strOption, array_map('strval', (array) $varValues), true) ? ' selected' : '';
 	}
 
 	/**