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.)

flow/flow_ebos_gasoil.cpp

@@ -0,0 +1,87 @@
+/*
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "config.h"
+
+// Define making clear that the simulator supports AMG
+#define FLOW_SUPPORT_AMG 1
+
+#include <flow/flow_ebos_gasoil.hpp>
+
+#include <opm/material/common/ResetLocale.hpp>
+#include <ewoms/models/blackoil/blackoiltwophaseindices.hh>
+
+#include <opm/grid/CpGrid.hpp>
+#include <opm/autodiff/SimulatorFullyImplicitBlackoilEbos.hpp>
+#include <opm/autodiff/FlowMainEbos.hpp>
+
+#if HAVE_DUNE_FEM
+#include <dune/fem/misc/mpimanager.hh>
+#else
+#include <dune/common/parallel/mpihelper.hh>
+#endif
+
+namespace Ewoms {
+namespace Properties {
+NEW_TYPE_TAG(EclFlowGasOilProblem, INHERITS_FROM(EclFlowProblem));
+
+//! The indices required by the model
+SET_PROP(EclFlowGasOilProblem, Indices)
+{
+private:
+    // it is unfortunately not possible to simply use 'TypeTag' here because this leads
+    // to cyclic definitions of some properties. if this happens the compiler error
+    // messages unfortunately are *really* confusing and not really helpful.
+    typedef TTAG(EclFlowProblem) BaseTypeTag;
+    typedef typename GET_PROP_TYPE(BaseTypeTag, FluidSystem) FluidSystem;
+
+public:
+    typedef Ewoms::BlackOilTwoPhaseIndices<GET_PROP_VALUE(TypeTag, EnableSolvent),
+                                           GET_PROP_VALUE(TypeTag, EnablePolymer),
+                                           GET_PROP_VALUE(TypeTag, EnableEnergy),
+                                           /*PVOffset=*/0,
+                                           /*disabledCompIdx=*/FluidSystem::waterCompIdx> type;
+};
+}}
+
+namespace Opm {
+void flowEbosGasOilSetDeck(Deck &deck, EclipseState& eclState, Schedule& schedule,  SummaryConfig& summaryConfig)
+{
+    typedef TTAG(EclFlowGasOilProblem) TypeTag;
+    typedef GET_PROP_TYPE(TypeTag, Vanguard) Vanguard;
+
+    Vanguard::setExternalDeck(&deck, &eclState, &schedule, &summaryConfig);
+}
+
+
+// ----------------- Main program -----------------
+int flowEbosGasOilMain(int argc, char** argv)
+{
+    // we always want to use the default locale, and thus spare us the trouble
+    // with incorrect locale settings.
+    Opm::resetLocale();
+
+#if HAVE_DUNE_FEM
+    Dune::Fem::MPIManager::initialize(argc, argv);
+#else
+    Dune::MPIHelper::instance(argc, argv);
+#endif
+
+    Opm::FlowMainEbos<TTAG(EclFlowGasOilProblem)> mainfunc;
+    return mainfunc.execute(argc, argv);
+}
+
+}