Changes to relaxIVdriver.cpp to compile using the Github based RelaxIV (#288)

I've edited this code for the Github based RelaxIV (https://github.com/frangio68/Min-Cost-Flow-Class/tree/master/MCFClass)to compile properly.

contrib/UnwrapComp/src/relaxIVdriver.cpp

@@ -2,6 +2,9 @@
 #include <sstream>
 #include <RelaxIV.h>
 #include <relaxIVdriver.h>
+#include <MCFClass.h>
+
+using namespace MCFClass_di_unipi_it;
 
 template<class T>
 inline T ABS( const T x )