refactor<Exception>: add context to exception to filter exceptions; each page has it's own error display control

src/Models/Exception.cs

@@ -1,15 +0,0 @@
-using System;
-
-namespace SourceGit.Models {
-
-    /// <summary>
-    ///     错误通知
-    /// </summary>
-    public static class Exception {
-        public static Action<string> Handler { get; set; }
-
-        public static void Raise(string error) {
-            Handler?.Invoke(error);
-        }
-    }
-}