make the build of flow fully parallelizable

so far, the actual specializations of the simulator were compiled into
the `libopmsimulators` library and the build of the glue code
(`flow.cpp`) thus needed to be deferred until the library was fully
built. Since the compilation of the glue code requires a full property
hierarchy for handling command line parameters, this arrangement
significantly increases the build time for systems with a sufficient
number of parallel build processes. ("sufficient" here means 8 or more
threads, i.e., a quadcore system with hyperthreading is sufficient
provided that it has enough main memory.)

the new approach is not to include these objects in
`libopmsimulators`, but to directly deal with them in the `flow`
binary. this allows all of them and the glue code to be compiled in
parallel.

compilation time on my machine before this change:

```
> touch ../opm/autodiff/BlackoilModelEbos.hpp; time make -j32 flow 2> /dev/null
Scanning dependencies of target opmsimulators
[  2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_gasoil.cpp.o
[  2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_oilwater.cpp.o
[  2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_blackoil.cpp.o
[  2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_solvent.cpp.o
[  4%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_polymer.cpp.o
[  6%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_energy.cpp.o
[  6%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_oilwater_polymer.cpp.o
[  6%] Linking CXX static library lib/libopmsimulators.a
[ 97%] Built target opmsimulators
Scanning dependencies of target flow
[100%] Building CXX object CMakeFiles/flow.dir/examples/flow.cpp.o
[100%] Linking CXX executable bin/flow
[100%] Built target flow

real    1m45.692s
user    8m47.195s
sys     0m11.533s
```

after:

```
> touch ../opm/autodiff/BlackoilModelEbos.hpp; time make -j32 flow 2> /dev/null
[ 91%] Built target opmsimulators
Scanning dependencies of target flow
[ 93%] Building CXX object CMakeFiles/flow.dir/flow/flow.cpp.o
[ 95%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_gasoil.cpp.o
[ 97%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_oilwater_polymer.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_polymer.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_oilwater.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_solvent.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_blackoil.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_energy.cpp.o
[100%] Linking CXX executable bin/flow
[100%] Built target flow

real    1m21.597s
user    8m49.476s
sys     0m10.973s
```

(this corresponds to a ~20% reduction of the time spend on waiting for
the compiler.)

CMakeLists.txt

@@ -113,11 +113,26 @@ if (NOT EIGEN3_FOUND)
 	add_dependencies (opmsimulators Eigen3)
 endif (NOT EIGEN3_FOUND)
 
-
-
 if (HAVE_OPM_TESTS)
     include (${CMAKE_CURRENT_SOURCE_DIR}/compareECLFiles.cmake)
 endif()
 
+opm_add_test(flow
+  ONLY_COMPILE
+  ALWAYS_ENABLE
+  DEPENDS "opmsimulators"
+  LIBRARIES "opmsimulators"
+  SOURCES
+    flow/flow.cpp
+    flow/flow_ebos_blackoil.cpp
+    flow/flow_ebos_gasoil.cpp
+    flow/flow_ebos_oilwater.cpp
+    flow/flow_ebos_polymer.cpp
+    flow/flow_ebos_solvent.cpp
+    flow/flow_ebos_energy.cpp
+    flow/flow_ebos_oilwater_polymer.cpp)
+install(TARGETS flow DESTINATION bin)
+
 include(OpmBashCompletion)
 opm_add_bash_completion(flow)
+

CMakeLists_files.cmake

@@ -23,17 +23,6 @@
 # originally generated with the command:
 # find opm -name '*.c*' -printf '\t%p\n' | sort
 list (APPEND MAIN_SOURCE_FILES
-	# place the flow_ebos_*.cpp files on top of the list because they
-	# take the longest to compile, and compiling them first speeds up
-	# parallel builds because it allows the jobserver to do better scheduling
-  opm/simulators/flow_ebos_blackoil.cpp
-  opm/simulators/flow_ebos_gasoil.cpp
-  opm/simulators/flow_ebos_oilwater.cpp
-  opm/simulators/flow_ebos_polymer.cpp
-  opm/simulators/flow_ebos_solvent.cpp
-  opm/simulators/flow_ebos_energy.cpp
-  opm/simulators/flow_ebos_oilwater_polymer.cpp
-
   opm/autodiff/Compat.cpp
   opm/autodiff/ExtractParallelGridInformationToISTL.cpp
   opm/autodiff/NewtonIterationBlackoilCPR.cpp
@@ -226,7 +215,6 @@ list (APPEND EXAMPLE_SOURCE_FILES
   examples/flow_legacy.cpp
   examples/flow_reorder.cpp
   examples/flow_sequential.cpp
-  examples/flow.cpp
   examples/sim_2p_incomp_ad.cpp
   examples/sim_2p_comp_reorder.cpp
   examples/sim_simple.cpp
@@ -252,7 +240,6 @@ list (APPEND PROGRAM_SOURCE_FILES
   examples/sim_2p_incomp.cpp
   examples/sim_2p_incomp_ad.cpp
   examples/sim_2p_comp_reorder.cpp
-  examples/flow.cpp
   examples/flow_legacy.cpp
   examples/flow_reorder.cpp
   examples/flow_sequential.cpp
@@ -447,13 +434,6 @@ list (APPEND PUBLIC_HEADER_FILES
   opm/polymer/TransportSolverTwophaseCompressiblePolymer.hpp
   opm/polymer/Point2D.hpp
   opm/polymer/TransportSolverTwophasePolymer.hpp
-  opm/simulators/flow_ebos_blackoil.hpp
-  opm/simulators/flow_ebos_gasoil.hpp
-  opm/simulators/flow_ebos_oilwater.hpp
-  opm/simulators/flow_ebos_polymer.hpp
-  opm/simulators/flow_ebos_solvent.hpp
-  opm/simulators/flow_ebos_energy.hpp
-  opm/simulators/flow_ebos_oilwater_polymer.hpp
   opm/simulators/ensureDirectoryExists.hpp
   opm/simulators/ParallelFileMerger.hpp
   opm/simulators/SimulatorCompressibleTwophase.hpp

flow/flow.cpp

@@ -20,13 +20,13 @@
 */
 #include "config.h"
 
-#include <opm/simulators/flow_ebos_blackoil.hpp>
-#include <opm/simulators/flow_ebos_gasoil.hpp>
-#include <opm/simulators/flow_ebos_oilwater.hpp>
-#include <opm/simulators/flow_ebos_solvent.hpp>
-#include <opm/simulators/flow_ebos_polymer.hpp>
-#include <opm/simulators/flow_ebos_energy.hpp>
-#include <opm/simulators/flow_ebos_oilwater_polymer.hpp>
+#include <flow/flow_ebos_blackoil.hpp>
+#include <flow/flow_ebos_gasoil.hpp>
+#include <flow/flow_ebos_oilwater.hpp>
+#include <flow/flow_ebos_solvent.hpp>
+#include <flow/flow_ebos_polymer.hpp>
+#include <flow/flow_ebos_energy.hpp>
+#include <flow/flow_ebos_oilwater_polymer.hpp>
 
 #include <opm/autodiff/SimulatorFullyImplicitBlackoilEbos.hpp>
 #include <opm/autodiff/FlowMainEbos.hpp>

flow/flow_ebos_blackoil.cpp

@@ -19,7 +19,7 @@
 // Define making clear that the simulator supports AMG
 #define FLOW_SUPPORT_AMG 1
 
-#include <opm/simulators/flow_ebos_blackoil.hpp>
+#include <flow/flow_ebos_blackoil.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <opm/grid/CpGrid.hpp>

flow/flow_ebos_energy.cpp

@@ -16,7 +16,7 @@
 */
 #include "config.h"
 
-#include <opm/simulators/flow_ebos_energy.hpp>
+#include <flow/flow_ebos_energy.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <opm/grid/CpGrid.hpp>

flow/flow_ebos_gasoil.cpp

@@ -19,7 +19,7 @@
 // Define making clear that the simulator supports AMG
 #define FLOW_SUPPORT_AMG 1
 
-#include <opm/simulators/flow_ebos_gasoil.hpp>
+#include <flow/flow_ebos_gasoil.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <ewoms/models/blackoil/blackoiltwophaseindices.hh>

flow/flow_ebos_oilwater.cpp

@@ -19,7 +19,7 @@
 // Define making clear that the simulator supports AMG
 #define FLOW_SUPPORT_AMG 1
 
-#include <opm/simulators/flow_ebos_oilwater.hpp>
+#include <flow/flow_ebos_oilwater.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <ewoms/models/blackoil/blackoiltwophaseindices.hh>

flow/flow_ebos_oilwater_polymer.cpp

@@ -19,7 +19,7 @@
 // Define making clear that the simulator supports AMG
 #define FLOW_SUPPORT_AMG 1
 
-#include <opm/simulators/flow_ebos_oilwater_polymer.hpp>
+#include <flow/flow_ebos_oilwater_polymer.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <ewoms/models/blackoil/blackoiltwophaseindices.hh>

flow/flow_ebos_polymer.cpp

@@ -16,7 +16,7 @@
 */
 #include "config.h"
 
-#include <opm/simulators/flow_ebos_polymer.hpp>
+#include <flow/flow_ebos_polymer.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <opm/grid/CpGrid.hpp>

flow/flow_ebos_solvent.cpp

@@ -16,7 +16,7 @@
 */
 #include "config.h"
 
-#include <opm/simulators/flow_ebos_solvent.hpp>
+#include <flow/flow_ebos_solvent.hpp>
 
 #include <opm/material/common/ResetLocale.hpp>
 #include <opm/grid/CpGrid.hpp>