#21 Private ctor and dtor for QLabellingView
Merge branch 'feature/task-version_1.2-CGAL_Arrangement' of https://github.com/oliviertournaire/QLabelling into feature/task-version_1.2-CGAL_Arrangement
Close #17 Add a dockable widget with arrangement info
Merge branch 'feature/task-version_1.2-CGAL_Arrangement' of https://github.com/oliviertournaire/QLabelling into feature/task-version_1.2-CGAL_Arrangement
Correct horizontal icon