Restart Tag System: Introduce Tag for OPM Extended Vectors

This is intended to supersede the RESTART_AUXILIARY tag.  There is
no practical difference between vectors that are needed for restart
and vectors that are not needed for restart.  They all go into the
SOLUTION section of a restart file.

Vectors tagged as RESTART_OPM_EXTENDED will not be output unless the
user does requests OPM-extended restart files.

opm/output/data/Cells.hpp

@@ -36,10 +36,10 @@ namespace data {
       from the TargetType enum which indicates why they they have been
       added to the container - and where they are headed.
 
-      RESTART_SOLUTION : Fields which represent primary variables, and
-       are reqired for restart. Typically pressure and
-       suturation. WIll end up in the SOLUTION section of the restart
-       file.
+     RESTART_SOLUTION : Cell-based quantities that are output to the
+       SOLUTION section of the restart file.  ECLIPSE-compatible names.
+       Many, but not necessarily all, of these quantities are required
+       for restarting the simulator.
 
      RESTART_AUXILIARY : Fields with extra information, not required
        for restart. Examples of this include fluid in place values or
@@ -52,6 +52,10 @@ namespace data {
        will not be output anywhere else.
 
      INIT : Fields which should go to the INIT file.
+
+     RESTART_OPM_EXTENDED: Cell-based quantities that are specific to
+       OPM-Flow.  Output only to extended OPM restart files.  Specifically
+       not output to ECLIPSE-compatible restart files.
     */
 
 
@@ -60,6 +64,7 @@ namespace data {
         RESTART_AUXILIARY,
         SUMMARY,
         INIT,
+        RESTART_OPM_EXTENDED,
     };
 
     /**

src/opm/output/eclipse/RestartIO.cpp

@@ -479,7 +479,8 @@ namespace {
         vectors.reserve(value.solution.size());
 
         for (const auto& [name, vector] : value.solution) {
-            if (vector.target == data::TargetType::RESTART_AUXILIARY)
+            if ((vector.target == data::TargetType::RESTART_AUXILIARY) ||
+                (vector.target == data::TargetType::RESTART_OPM_EXTENDED))
             {
                 vectors.push_back(name);
             }