added is null or emtpy and is null or whitespace extension methods

VectoCommon/VectoCommon/Utils/StringExtensionMethods.cs

@@ -84,6 +84,16 @@ namespace TUGraz.VectoCommon.Utils
 			return int.Parse(self) != 0;
 		}
 
+		public static bool IsNullOrEmpty(this string self)
+		{
+			return string.IsNullOrEmpty(self);
+		}
+
+		public static bool IsNullOrWhiteSpace(this string self)
+		{
+			return string.IsNullOrWhiteSpace(self);
+		}
+
 		public static double IndulgentParse(this string self) =>
 			double.Parse(new string(self.Trim().TakeWhile(c => char.IsDigit(c) || c == '.').ToArray()),
 				CultureInfo.InvariantCulture);