箭头分离到独立的model中，方便自定义path

AIStudio.Wpf.DiagramDesigner/ViewModels/AdditionViewModel/Interface/IFontViewModel.cs

@@ -0,0 +1,27 @@
+using System.ComponentModel;
+using System.Windows;
+using System.Windows.Media;
+
+namespace AIStudio.Wpf.DiagramDesigner
+{
+    public interface IFontViewModel
+    {
+        string FontFamily { get; set; }
+        Color FontColor { get; set; }
+        double FontSize { get; set; }  
+        Color TextEffectColor { get; set; }
+        Color HighlightColor { get; set; }
+        FontCase FontCase { get; set; }
+        FontWeight FontWeight { get; set; }
+        FontStyle FontStyle { get; set; }    
+        FontStretch FontStretch { get; set; }
+        bool Underline { get; set; }
+        bool Strikethrough { get; set; }
+        bool OverLine { get; set; }
+        HorizontalAlignment HorizontalAlignment { get; set; }
+        VerticalAlignment VerticalAlignment { get; set; }
+        double LineHeight { get; set; }
+        event PropertyChangedEventHandler PropertyChanged;
+
+    }
+}