Incorporate Extended Network Objects From Restart into Schedule

This commit hooks the new RstNetwork object into the restart feature
of the main Schedule object.  We form ExtNetwork Schedule subobjects
if there are active branches and nodes in the restart file.

opm/io/eclipse/rst/state.hpp

@@ -28,6 +28,7 @@
 #include <opm/io/eclipse/rst/action.hpp>
 #include <opm/io/eclipse/rst/group.hpp>
 #include <opm/io/eclipse/rst/header.hpp>
+#include <opm/io/eclipse/rst/network.hpp>
 #include <opm/io/eclipse/rst/udq.hpp>
 #include <opm/io/eclipse/rst/well.hpp>
 
@@ -61,6 +62,7 @@ struct RstState {
     ::Opm::UnitSystem unit_system;
     RstHeader header;
     RstAquifer aquifers;
+    RstNetwork network;
     std::vector<RstWell> wells;
     std::vector<RstGroup> groups;
     std::vector<RstUDQ> udqs;