Add value property to quality .NET (#217)

- Added ushort quality  property.

Co-authored-by: Andrew Moorcroft <andrew.moorcroft@nortechonline.co.uk>

dotnet/IEC61850forCSharp/IEC61850CommonAPI.cs

@@ -178,7 +178,7 @@ namespace IEC61850
 		/// </summary>
 		public class Quality
 		{
-			private UInt16 value;
+			private UInt16 value;		
 
 			private const UInt16 QUALITY_DETAIL_OVERFLOW = 4;
 			private const UInt16 QUALITY_DETAIL_OUT_OF_RANGE = 8;
@@ -193,6 +193,8 @@ namespace IEC61850
 			private const UInt16 QUALITY_OPERATOR_BLOCKED = 4096;
 			private const UInt16 QUALITY_DERIVED = 8192;
 
+			public ushort Value => value;
+
 			public override string ToString ()
 			{
 				return GetValidity ().ToString ();