Rather than instantiating a UTF8 encoding everywhere when we want to supress the BOM, use a single Util.UTF8NoBomEncoding.

This class is thread-safe (as evidenced by the provision of the system-wide Encoding.UTF8 which does not suppress BOM on output).

OpenSim/Framework/Util.cs

@@ -148,6 +148,7 @@ namespace OpenSim.Framework
         }
 
         public static Encoding UTF8 = Encoding.UTF8;
+        public static Encoding UTF8NoBomEncoding = new UTF8Encoding(false);
 
         /// <value>
         /// Well known UUID for the blank texture used in the Linden SL viewer version 1.20 (and hopefully onwards)