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.)
