Add Ctrl + C support

signal_handler.ts

@@ -0,0 +1,8 @@
+import { TaskManager } from "./task_manager.ts";
+
+export function add_exit_handler(m: TaskManager) {
+    const handler = () => {
+        m.close();
+    };
+    Deno.addSignalListener("SIGINT", handler);
+}