vle.discrete-time: enabling to initialize Var history and Vect inside constructor

[Chabrier]

• Providing a C++ initialisation method enabling to initialize a Var with history from the constructor with a tuple.
• Providing a C++ initialisation method enabling to initialize a Vector with history from the constructor with a matrix.
• Providing a C++ initialisation method enabling to initialize a Vector without history from the constructor with a tuple.