Desire dependencies are not implemented

[mamaheux]

Steps :

• Remove the following difference in the README.md file: Desires cannot have dependencies;
• In the DesireSetObserver class, add the following parameter to onDesireSetChanged : const std::unordered_map<uint64_t, std::unordered_set<uint64_t>>& desireDependenciesById
• In the DesireSetObserver class, create an empty implementation for onDesireSetChanged.
• In the DesireSetObserver class, add the following method: virtual void onDesireFulfilled(uint64_t desireId).
• In the DesireSet class, add the following field: std::unordered_map<uint64_t, std::unordered_set<uint64_t>> m_desiredependenciesById;.
• In the DesireSet class, make the method removeDesire remove all the dependencies recursively.
• In the DesireSet class, add overload methods of addDesire that take a std::unordered_set<uint64_t> as the first parameter.
• In the DesireSet class, add a private method that makes the desire fulfilled. The method removes the desire from m_desiresById, removes the desire id from all set in desireDependenciesById and call onDesireFulfilled of the observers.
• In the DesireSet class, make BaseStrategy a friend class.
• In the BaseStrategy class, make the DesireSet private.
• In the BaseStrategy, add a method that makes the current desire fulfilled by calling the method of the DesireSet. Make sure the desire id is valid.
• In the Solver and GecodeSolver classes, add the following parameter to the solve method: const std::unordered_map<uint64_t, std::unordered_set<uint64_t>>& desireDependenciesById
• In the Solver class, the selectMostIntenseEnabledDesireIndexes must only index that does not have any dependencies. Rename the method accordingly.