Merge pull request #21 from jeremyletang/raw-pointer

prepare rgtk to the new raw pointer reform
New widget : AppChooserDialog
-> however, not all of its functionalities work since an error prevent me to test it...
Remove warnings
Merge pull request #23 from GuillaumeGomez/master

New widget : AppChooserDialog
continue to fix pointers
finalize port to the new raw pointers form