add function to get just the *value* of the attribute

app/lib/phast/Parser/XMLParser.inc.php

@@ -164,7 +164,15 @@
 			return $str;
 		}
 
-		public function GetAttribute($name, $index = 0)
+		public function GetAttributeValue($name, $index = 0) : ?string
+		{
+			$attr = $this->GetAttribute($name, $index);
+			if ($attr != null)
+				return $attr->Value;
+			return null;
+		}
+		
+		public function GetAttribute($name, $index = 0) : ?MarkupAttribute
 		{
 			$i = 0;
 			$last = null;