- Added an UNFINISHED EntitiesSelection class.
- Added an AbstractEntitiesSet interface. Now EntitiesSet inherits from AbstractEntitiesSet.
- Added a missing license heaer in camera.cpp.
- Now EntitiesSelection inherits from AbstractEntitiesSet and Observer classes ().
- Defined all the needed methods in EntitiesSelection class.
- Minor fixes in multiple classes for solving ambiguity errors.
- Added initialization code in EntitiesManager constructor.
- Added methods createUserSelection() and removeUserSelection() in EntitiesManager class.
- Now EntitiesManager is a friend class of LightsManager.
- Added a EntitiesSelection::size() getter.