Add Parallel Calculation Support for WBPn/WPAVE

This commit adds a parallel calculation object derived from the serial
PAvgCalculator class.  This parallel version is aware of MPI
communicators and knows how to aggregate contributions from wells that
might be distributed across ranks.

We also add a wrapper class, ParallelWBPCalculation, which knows how to
exchange information from PAvgCalculatorCollection objects on different
ranks and, especially, how to properly prune inactive cells/connections.

CMakeLists.txt

@@ -415,6 +415,46 @@ opm_add_test(test_parallel_wbp_sourcevalues_np4
     4
 )
 
+opm_add_test(test_parallel_wbp_calculation
+  SOURCES
+    tests/test_parallel_wbp_calculation.cpp
+  LIBRARIES
+    opmsimulators ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}
+  CONDITION
+    MPI_FOUND AND Boost_UNIT_TEST_FRAMEWORK_FOUND
+  ONLY_COMPILE
+)
+
+opm_add_test(test_parallel_wbp_calculation_create
+  EXE_NAME
+    test_parallel_wbp_calculation
+  CONDITION
+    MPI_FOUND AND Boost_UNIT_TEST_FRAMEWORK_FOUND
+  DRIVER_ARGS
+    -n 2
+    -b ${PROJECT_BINARY_DIR}
+  TEST_ARGS
+    --run_test=Create
+  NO_COMPILE
+  PROCESSORS
+    2
+)
+
+opm_add_test(test_parallel_wbp_calculation_well_openconns
+  EXE_NAME
+    test_parallel_wbp_calculation
+  CONDITION
+    MPI_FOUND AND Boost_UNIT_TEST_FRAMEWORK_FOUND
+  DRIVER_ARGS
+    -n 2
+    -b ${PROJECT_BINARY_DIR}
+  TEST_ARGS
+    --run_test=TopOfFormation_Well_OpenConns
+  NO_COMPILE
+  PROCESSORS
+    2
+)
+
 opm_add_test(test_broadcast
   DEPENDS "opmsimulators"
   LIBRARIES opmsimulators ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}