Using Blessed with Vorpal causes two characters input instead of one

Using [Blessed](https://github.com/chjj/blessed) in conjunction with Vorpal like this:

```javascript
const blessed = require('blessed')
const vorpal = require('vorpal')()

const program = blessed.program() // Commenting this out means normal behaviour

vorpal
.command('test')
.action(function (args, cb) {
this.log('Good luck getting to this command!')
cb()
})

vorpal
.delimiter('> ')
.show()
```

Causes output like this:

```bash
➔ node minimal.js
> tteesstt

Invalid Command. Showing Help:

Commands:

help [command...] Provides help for a given command.
exit Exits application.
test

>
>
```

As you can probably tell, **every keystroke is sent / read twice**, even the "return" key.
My guess is that Blessed attaches their own listener, and emits the event as well? Just a guess, though.

Maybe someone with knowledge of Blessed can help me out?