AddChildWidget load sub-dependencies

* fix sub-dependecies loading when missing
SlideShow plugin (ChoiceList)

+ Timed slideshow plugin, used on ChoiceList
Merge branch 'master' of github.com:Heigvd/Wegas

# By Benjamin Gerber
# Via Benjamin Gerber
* 'master' of github.com:Heigvd/Wegas:
  pmg adapt gamemodel at new client script
  pmg - can impact task requirements