Adds a new constructor to Main.hpp that takes shared pointers to Deck,
EclipseState, Schedule, and SummaryConfig. This makes it possible to
share these variables with Python without worrying about lifetime issues
of the underlying C++ objects. For example, a Python script can first
create an opm.io.schedule.Schedule object which is modified from Python.
Then, assume the same Python script creates an
opm.simulators.BlackOilSimulator which is initialized with the same
schedule object. Since the underlying C++ object is a shared pointer,
the Schedule object in Python may go out of scope (get deleted by Python)
without having the C++ schedule object being deleted. And the Python
BlackOilSimulator may continue to be used after the Python Schedule object
has been deleted since it still has a valid C++ schedule object.
Restores the original cwd after each unittest in test_basic.py. Also
simplifies add_test() in python/simulators/CMakeLists.txt such that the
Bash script wrapper run-python-tests.sh is no longer needed to run the
tests.
