Made the Nonce class's constructors and a couple of properties internal.

This is a breaking change from v1.0, but they really shouldn't have been public in the first place.  It's doubtful that anyone needs these members, which is why they should be removed and why they can be removed.

src/DotNetOpenId/Nonce.cs

@@ -24,7 +24,7 @@ public class Nonce {
 				AllowedCharacters[i++] = j;
 		}
 
-		public Nonce() : this(DateTime.UtcNow, generateUniqueFragment(), false) { }
+		internal Nonce() : this(DateTime.UtcNow, generateUniqueFragment(), false) { }
 		/// <summary>
 		/// Deserializes a nonce from a string passed to us.
 		/// </summary>
@@ -34,7 +34,7 @@ public class Nonce {
 		/// 2005-05-15T17:11:51ZUNIQUE
 		/// </param>
 		/// <param name="remoteServerOrigin"></param>
-		public Nonce(string code, bool remoteServerOrigin) {
+		internal Nonce(string code, bool remoteServerOrigin) {
 			if (string.IsNullOrEmpty(code)) throw new ArgumentNullException("code");
 			Code = code;
 			int indexOfDateEnd = code.IndexOf("Z", StringComparison.Ordinal);
@@ -51,7 +51,7 @@ public class Nonce {
 		}
 
 		public string Code { get; internal set; }
-		public DateTime CreationDate { get; internal set; }
+		internal DateTime CreationDate { get; set; }
 		internal string UniqueFragment { get; set; }
 		bool remoteServerOrigin;
 		TimeSpan maximumLifetime {
@@ -62,7 +62,7 @@ public class Nonce {
 			}
 		}
 
-		public TimeSpan Age { get { return DateTime.UtcNow - CreationDate.ToUniversalTime(); } }
+		internal TimeSpan Age { get { return DateTime.UtcNow - CreationDate.ToUniversalTime(); } }
 		public bool IsExpired { get { return Age > maximumLifetime; } }
 		/// <summary>
 		/// Gets the date past which this nonce is no longer valid, so storing a nonce for replay attack