Fixes another off-by-one issue when diffing with caching

Refactored commands and blame annotations

src/commands/commands.ts

@@ -0,0 +1,33 @@
+'use strict'
+import {commands, Disposable, TextEditor, TextEditorEdit} from 'vscode';
+import {Commands} from '../constants';
+
+export abstract class Command extends Disposable {
+    private _subscriptions: Disposable;
+
+    constructor(command: Commands) {
+        super(() => this.dispose());
+        this._subscriptions = commands.registerCommand(command, this.execute, this);
+    }
+
+    dispose() {
+        this._subscriptions && this._subscriptions.dispose();
+    }
+
+    abstract execute(...args): any;
+}
+
+export abstract class EditorCommand extends Disposable {
+    private _subscriptions: Disposable;
+
+    constructor(command: Commands) {
+        super(() => this.dispose());
+        this._subscriptions = commands.registerTextEditorCommand(command, this.execute, this);
+    }
+
+    dispose() {
+        this._subscriptions && this._subscriptions.dispose();
+    }
+
+    abstract execute(editor: TextEditor, edit: TextEditorEdit, ...args): any;
+}