Isconnecting (#803)

* Add IsConnecting property to determine whether the multiplexor is trying to establish a connection.
* spaces
* Use the correct enum to determine 'IsConnecting'

Author: Richard Tappenden

StackExchange.Redis/StackExchange/Redis/ConnectionMultiplexer.cs

@@ -1839,6 +1839,20 @@ public bool IsConnected
             }
         }
 
+        /// <summary>
+        /// Indicates whether any servers are currently trying to connect
+        /// </summary>
+        public bool IsConnecting
+        {
+            get
+            {
+                var tmp = serverSnapshot;
+                for (int i = 0; i < tmp.Length; i++)
+                    if (tmp[i].IsConnecting) return true;
+                return false;
+            }
+        }
+
         internal ConfigurationOptions RawConfig => configuration;
 
         internal ServerSelectionStrategy ServerSelectionStrategy => serverSelectionStrategy;

StackExchange.Redis/StackExchange/Redis/Interfaces/IConnectionMultiplexer.cs

@@ -51,6 +51,11 @@ public interface IConnectionMultiplexer
         /// </summary>
         bool IsConnected { get; }
 
+        /// <summary>
+        /// Indicates whether any servers are connected
+        /// </summary>
+        bool IsConnecting { get; }
+
         /// <summary>
         /// Should exceptions include identifiable details? (key names, additional .Data annotations)
         /// </summary>

StackExchange.Redis/StackExchange/Redis/PhysicalBridge.cs

@@ -70,6 +70,8 @@ public enum State : byte
 
         public bool IsConnected => state == (int)State.ConnectedEstablished;
 
+        public bool IsConnecting => state == (int)State.ConnectedEstablishing || state == (int)State.Connecting;
+
         public ConnectionMultiplexer Multiplexer { get; }
 
         public ServerEndPoint ServerEndPoint { get; }

StackExchange.Redis/StackExchange/Redis/ServerEndPoint.cs

@@ -77,6 +77,8 @@ public ServerEndPoint(ConnectionMultiplexer multiplexer, EndPoint endpoint, Text
 
         public bool IsConnected => interactive?.IsConnected == true;
 
+        public bool IsConnecting => interactive?.IsConnecting == true;
+        
         internal Exception LastException
         {
             get