Added array serialization option, adjusted array converter

CryptoExchange.Net/Objects/Enums.cs

@@ -82,4 +82,19 @@
         /// </summary>
         Bid
     }
+
+    /// <summary>
+    /// Define how array parameters should be send
+    /// </summary>
+    public enum ArrayParametersSerialization
+    {
+        /// <summary>
+        /// Send multiple key=value for each entry
+        /// </summary>
+        MultipleValues,
+        /// <summary>
+        /// Create an []=value array
+        /// </summary>
+        Array
+    }
 }