data preparation (issue #21)

This version introduces multiple enhancements:

added functions to change data before add to object and before get from object
allowed to use functions objects and lambda functions
rebuild call user function

Details of additions/deletions below:
--------------------------------------------------------------

Modified:   Base/BlueObject.php
            -- Added --
                _dataPreparation, allow to prepare data by given functions
            -- Updated --
                getData added handling of _dataPreparation
                traveler, changed variables given to methods
                _recursiveTraveler, changed variables given to methods
                _callUserFunction, rebuild usage of call_user_func
                _putData added handling of _dataPreparation