Changed WaitOne() to WaitOneAsync() in websocket send

CryptoExchange.Net/ExtensionMethods.cs

@@ -223,6 +223,16 @@ namespace CryptoExchange.Net
             }
         }
 
+        /// <summary>
+        /// Wait one async
+        /// </summary>
+        /// <param name="handle"></param>
+        /// <returns></returns>
+        public static Task<bool> WaitOneAsync(this WaitHandle handle)
+        {
+            return handle.WaitOneAsync(-1, CancellationToken.None);
+        }
+
         /// <summary>
         /// Wait one async
         /// </summary>

CryptoExchange.Net/Sockets/CryptoExchangeWebSocketClient.cs

@@ -352,7 +352,7 @@ namespace CryptoExchange.Net.Sockets
                 if (_closing)
                     break;
 
-                _sendEvent.WaitOne();
+                await _sendEvent.WaitOneAsync().ConfigureAwait(false);
 
                 if (_closing)                
                     break;
@@ -365,7 +365,8 @@ namespace CryptoExchange.Net.Sockets
                         DateTime? start = null;
                         while (MessagesSentLastSecond() >= RatelimitPerSecond)
                         {
-                            start = DateTime.UtcNow;
+                            if (start == null)
+                                start = DateTime.UtcNow;
                             await Task.Delay(10).ConfigureAwait(false);
                         }