Python bindings for the blackoil simulator.

A simplified version of PR #2518 that uses a deck filename to construct
the simulator.

After private discussion with @joakim-hove it was decided that the
construction of the blackoil simulator from Python using deck,
ecliseState, schedule and summaryConfig as constructor arguments from
\#2518 should be replaced by a constructor taking only the deck filename
as parameter.

A rewrite of the Python bindings for the blackoil simulator using
pybind11 as introduced in PR #2127. The new version uses the
refactored flow.cpp introduced in PR #2516 and thus avoids duplication
of the code in simulators.cpp.

This PR will be the starting point for implementing the Python bindings
introduced in PR #2403.

python/CMakeLists.txt

@@ -1,3 +1,4 @@
 if(NOT TARGET pybind11)
   add_subdirectory( pybind11 )
+  add_subdirectory( simulators )
 endif()

python/simulators/CMakeLists.txt

@@ -0,0 +1,11 @@
+pybind11_add_module(simulators simulators.cpp)
+
+set_target_properties( simulators PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/python/opm2 )
+
+target_sources(simulators
+  PRIVATE
+    ../../flow/flow_ebos_blackoil.cpp)
+
+target_link_libraries( simulators PRIVATE opmsimulators )
+
+install(TARGETS simulators DESTINATION ${PYTHON_INSTALL_PREFIX}/simulators)

python/simulators/simulators.cpp

@@ -0,0 +1,38 @@
+#include "config.h"
+#include <opm/parser/eclipse/Deck/Deck.hpp>
+#include <opm/parser/eclipse/EclipseState/EclipseState.hpp>
+#include <opm/parser/eclipse/EclipseState/Schedule/Schedule.hpp>
+#include <opm/parser/eclipse/EclipseState/SummaryConfig/SummaryConfig.hpp>
+#define FLOW_BLACKOIL_ONLY
+#include <opm/simulators/flow/Main.hpp>
+#include <pybind11/pybind11.h>
+#include <pybind11/embed.h>
+#include <iostream>
+#include <string>
+
+namespace py = pybind11;
+
+class BlackOilSimulator
+{
+public:
+
+    BlackOilSimulator( const std::string &deckFilename) : deckFilename_(deckFilename)
+    {
+    }
+
+    int run()
+    {
+        auto mainObject = Opm::Main( deckFilename_ );
+        return mainObject.runDynamic();
+    }
+    
+private:
+    const std::string deckFilename_;
+};
+
+PYBIND11_MODULE(simulators, m)
+{
+    py::class_<BlackOilSimulator>(m, "BlackOilSimulator")
+        .def(py::init< const std::string& >())
+        .def("run", &BlackOilSimulator::run);
+}