Add xterm itegration

* Move to TypeScript from legacy JavaScript
* Add support of xterm.js
* Hterm is still available for backward compatibility

js/typings/htermLib/index.d.ts

@@ -0,0 +1,11 @@
+export interface Storage {
+}
+
+export interface Memory {
+    new (): Storage;
+    Memory(): Storage
+}
+
+export var Storage: {
+    Memory: Memory
+};