Added support for Patch requests, added SetBody to ParameterCollection for directly setting the request body

CryptoExchange.Net/Objects/Constants.cs

@@ -13,5 +13,9 @@
         /// Form content type header
         /// </summary>
         public const string FormContentHeader = "application/x-www-form-urlencoded";
+        /// <summary>
+        /// Placeholder key for when request body should be set to the value of this KVP
+        /// </summary>
+        public const string BodyPlaceHolderKey = "_BODY_";
     }
 }

CryptoExchange.Net/Objects/ParameterCollection.cs

@@ -3,6 +3,7 @@ using CryptoExchange.Net.Converters.SystemTextJson;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
+using System.Linq;
 
 namespace CryptoExchange.Net.Objects
 {
@@ -193,5 +194,18 @@ namespace CryptoExchange.Net.Objects
                 Add(key, int.Parse(stringVal));
             }
         }
+
+        /// <summary>
+        /// Set the request body. Can be used to specify a simple value or array as the body instead of an object
+        /// </summary>
+        /// <param name="body">Body to set</param>
+        /// <exception cref="InvalidOperationException"></exception>
+        public void SetBody(object body)
+        {
+            if (this.Any())
+                throw new InvalidOperationException("Can't set body when other parameters already specified");
+
+            Add(Constants.BodyPlaceHolderKey, body);
+        }
     }
 }