Add function parser

StructureHelperCommon/Infrastructures/Interfaces/IOneVariableFunction.cs

@@ -25,6 +25,7 @@ namespace StructureHelperCommon.Infrastructures.Interfaces
         public double MinArg { get; set; }
         public double MaxArg { get; set; }
         public Color Color { get; set; }
+        public string Trace { get; set; }
         public ObservableCollection<IOneVariableFunction> Functions { get; set; }
         public bool Check();
         public double GetByX(double xValue);