Introduce Disposable abstract class

src/common/Lifecycle.ts

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) 2018 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IDisposable } from 'xterm';
+
+export abstract class Disposable implements IDisposable {
+  protected _disposables: IDisposable[] = [];
+
+  constructor() {
+  }
+
+  public dispose(): void {
+    this._disposables.forEach(d => d.dispose());
+    this._disposables.length = 0;
+  }
+
+  public register<T extends IDisposable>(t: T): void {
+    this._disposables.push(t);
+  }
+}