Character :  using shared_ptr; temporarily removed persona list
Maths : Vec3f is no more a typedef, instead in inherits from Vector< float, 3 >
Personna : using shared_ptr ; removed many attributs, added home and workplace attributes.
Chronologies : there are now 4 distincts types of chronologies, inheriting PropertyChronology < T >
 - > periodic constant, periodic linear, absolute constant, absolute linear