Cleanup.
Add app implementation.
Ensure single instance application.
Remove deprecated stuff.
Add version information.
Add make_unique.
Add mainwindow.
ActionManager implementation.
Initialize actions.
Add getters and setters.
Add action groups.
Merge branch 'actions-and-menus' into newstructure
MenuManager implementation.
Cleanup includes.
Add menu getters.
Initialize menus.
Add submenus.
Add getters and setters.
Add methods for adding actions.
Rename methods.