Add cask for Textual 2.1.1
user
```ruby
class Textual < Cask
  url 'http://www.codeux.com/textual/private/downloads/builds/Textual_Demo_12536.zip'
  homepage 'http://www.codeux.com/textual/'
  version '2.1.1'
  sha1 'af057d11e3578afa3b80f4f26093978389982ca2'
end
```
assistant