Add copy constructor and assignement for navigator.
Add copy constructor and assignement for navigator.

rdebroiz/dtk,NicolasSchnitzler/dtk,d-tk/dtk,d-tk/dtk,d-tk/dtk,rdebroiz/dtk,d-tk/dtk,d-tk/dtk,NicolasSchnitzler/dtk,rdebroiz/dtk,NicolasSchnitzler/dtk,d-tk/dtk,NicolasSchnitzler/dtk,rdebroiz/dtk