Refactored MtApi4 (MT4) for working with new architecture

MtApi/Events/MtChartEvent.cs

@@ -6,6 +6,6 @@
         public int EventId { get; set; }
         public long Lparam { get; set; }
         public double Dparam { get; set; }
-        public string Sparam { get; set; }
+        public string Sparam { get; set; } = string.Empty;
     }
 }

MtApi/Events/MtEventTypes.cs

@@ -4,6 +4,7 @@
     {
         LastTimeBar = 1,
         ChartEvent  = 2,
-        OnLockTicks = 3
+        OnLockTicks = 3,
+        OnTick      = 4
     }
 }

MtApi/Events/OnLockTicksEvent.cs

@@ -2,6 +2,6 @@
 {
     internal class OnLockTicksEvent
     {
-        public string Instrument { get; set; }
+        public string Instrument { get; set; } = string.Empty;
     }
 }