Removed the stylus folder and added stylus.js with doctest to lib/pixi

lib/pixi/bundle.js

@@ -12,6 +12,7 @@ import Button from './button.js'
 import ButtonGroup from './buttongroup.js'
 import Scrollview from './scrollview.js'
 import Slider from './slider.js'
+import Stylus from './stylus.js'
 import Switch from './switch.js'
 import Popup from './popup.js'
 import PopupMenu from './popupmenu.js'
@@ -44,6 +45,7 @@ window.Button = Button
 window.ButtonGroup = ButtonGroup
 window.Scrollview = Scrollview
 window.Slider = Slider
+window.Stylus = Stylus
 window.Switch = Switch
 window.Popup = Popup
 window.PopupMenu = PopupMenu