Feature/update settings (#225)

Added SetOptions method to update client settings
Added SocketConnection parameter to PeriodicQuery callback
Added setting of DefaultProxyCredentials on HttpClient instance when client is not provided by DI
Added support for overriding request time out per request
Changed max wait time for close handshake response from 5 seconds to 1 second
Fixed exception in trade tracker when there is no data in the initial snapshot

CryptoExchange.Net/Objects/Options/UpdateOptions.cs

@@ -0,0 +1,29 @@
+using CryptoExchange.Net.Authentication;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace CryptoExchange.Net.Objects.Options
+{
+    /// <summary>
+    /// Options to update
+    /// </summary>
+    public class UpdateOptions<T> where T : ApiCredentials
+    {
+        /// <summary>
+        /// Proxy setting. Note that if this is not provided any previously set proxy will be reset
+        /// </summary>
+        public ApiProxy? Proxy { get; set; }
+        /// <summary>
+        /// Api credentials
+        /// </summary>
+        public T? ApiCredentials { get; set; }
+        /// <summary>
+        /// Request timeout
+        /// </summary>
+        public TimeSpan? RequestTimeout { get; set; }
+    }
+
+    /// <inheritdoc />
+    public class UpdateOptions : UpdateOptions<ApiCredentials> { }
+}