api: provide an api `.fire()` to remove related event from stream

See the title of this PR, I did:

##### 1. add `.fire()`
this call `removeListener()` to our `onData`/`onNewListener` functions for user, and if user has a specific call to `enableMouse`, it would call `disableMouse()`.

##### 2. remove some unnecessary calls at user-land
for example: user don't need write this:
```js
process.on('exit', function() {
  keypress.disableMouse();
});
```

All what I did just fix some memory leaks on `EventEmitter`.
PS: This module is very awesome, thank you so much :)