-Restor nb_var in Ctc and Pdc
-Creation of Ctc(const Array<Ctc>& l) to initialized a contractor with a
list of contractor
-Creation of Pdc(const Array<Pdc>& l) to initialized a contractor with a
list of contractor
-Remove init_lp in the constractor of CtcPolytopeHull
-Extend to 12 variables the contactor CtcExistr
correct some mistake
Now Ctc() is equivalent to nb_var=-1
correct a lot  of Warning  [-Wsign-compare]
Correct:
Ctc();
Ctc(int n);
Pdc();
Pdc(int n);
correct some warnings
Remove some warnings
undo some modification about (unsigned int) and (int)
Add new function,
In ibex_Affine2Eval.h:
ExprLabel& eval_label(const Function& f, const Affine2Vector& box)
Affine2Domain& eval(const Function& f, const Affine2Vector& box) 

In ibex_Function.h:
void write_arg_af2_domains(const Affine2Vector& box) 
Affine2        eval_affine2 (const Affine2Vector& box) 
Affine2Domain& eval_affine2_affinedomain(const Affine2Vector& box)
Affine2Vector  eval_affine2_vector (const Affine2Vector& affine)
Affine2Matrix  eval_affine2_matrix (const Affine2Vector& box)
Remove declaration of counters outside of the loops
contractor: Minor change
correct a bug on Mac OSX
Remove Ctc() and Pdc()
Remove all the constructorwhich need the nb_var
correct a bug in Function::eval_affine2
Removing vibes interface
Update sphinx config file
doc update