Bastien Penavayre authored Apr 26, 2016 and Hugo Beauzée-Luyssen committed Apr 26, 2016

-New class Dialog (see Dialog.hpp) that wraps the internal type libvlc_dialog_id and associated functions
-Alter the Instance class (Instance.hpp), so that it holds the callbacks relative to the dialog module:
        -Inherits from CallbackOwner<8> instead of CallbackOwner<2>
        -Holder a std::shared_ptr<libvlc_dialog_cbs>
        -public usings for the prototype of the new callbacks
        -setDialogHandlers/unsetDialogHandlers
        -update the default constructor

Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>