2017-11-27:
 - Change parser to fit with specifications 3.0.5
 - Add annotations: decision variables
 - Add sum and alldif and expressions with expression (aka intension constraint instead of variables)
 - New callbacks:
     void beginAnnotations()
     void endAnnotations()
     void buildAnnotationDecision(vector<XVariable *> list)
     void buildConstraintOrdered(string id, vector<XVariable *> &list, vector<int> &lengths, OrderType order)
     void buildConstraintAlldifferent(string id, vector<Tree *> &list)
     void buildConstraintSum(string id, vector<Tree *> &trees, XCondition &cond)
     void buildConstraintSum(string id, vector<Tree *> &trees, vector<int> & coeffs, XCondition &cond)


2017-10-20:
 - Stop to use regex for primitive recognition
 - Canonization of intension constraints.
 - New primitives recognition
 - New option in the callback: intensionUsingString, false by default
 - New callbacks:
     void buildConstraintPrimitive(string id, OrderType op, XVariable *x, int k):  x <op> k
     void buildConstraintPrimitive(string id, XVariable *x, int min, int max, bool negated): x>=min and x<=max