Capture More Dynamic State Per Segment

In particular, calculate segment flow velocities, segment holdup
fractions, and segment phase viscosities when updating the well
state.  This is purely for reporting purposes and does not affect
the multisegmented model.

opm/simulators/wells/MultisegmentWellEval.hpp

@@ -35,6 +35,8 @@
 
 #include <array>
 #include <memory>
+#include <utility>
+#include <vector>
 
 namespace Dune {
 template<class Matrix> class UMFPack;