Replace DnDns with HeijdenDns

HeijdenDns seems to do a better job at querying SRV records

MinecraftClient/Protocol/Dns/Records/RecordMX.cs

@@ -0,0 +1,59 @@
+using System;
+
+namespace Heijden.DNS
+{
+	/*
+	3.3.9. MX RDATA format
+
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		|                  PREFERENCE                   |
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+		/                   EXCHANGE                    /
+		/                                               /
+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
+
+	where:
+
+	PREFERENCE      A 16 bit integer which specifies the preference given to
+					this RR among others at the same owner.  Lower values
+					are preferred.
+
+	EXCHANGE        A <domain-name> which specifies a host willing to act as
+					a mail exchange for the owner name.
+
+	MX records cause type A additional section processing for the host
+	specified by EXCHANGE.  The use of MX RRs is explained in detail in
+	[RFC-974].
+	*/
+
+	public class RecordMX : Record, IComparable
+	{
+		public ushort PREFERENCE;
+		public string EXCHANGE;
+
+		public RecordMX(RecordReader rr)
+		{
+			PREFERENCE = rr.ReadUInt16();
+			EXCHANGE = rr.ReadDomainName();
+		}
+
+		public override string ToString()
+		{
+			return string.Format("{0} {1}", PREFERENCE, EXCHANGE);
+		}
+
+		public int CompareTo(object objA)
+		{
+			RecordMX recordMX = objA as RecordMX;
+			if (recordMX == null)
+				return -1;
+			else if (this.PREFERENCE > recordMX.PREFERENCE)
+				return 1;
+			else if (this.PREFERENCE < recordMX.PREFERENCE)
+				return -1;
+			else // they are the same, now compare case insensitive names
+				return string.Compare(this.EXCHANGE, recordMX.EXCHANGE, true);
+		}
+
+	}
+}