Andreas Dedner authored 7 years ago and Matthew Collins committed 6 years ago

test for a BCRSMatrix<BCSRMatrix>

before when initialising a BCRSMatrix you had to write
BCRSMatrix.implicit or BCRSMatrix11.implicit this has changed to
BuildMode.implicit. Some cleanup as well all demos files had to now use
this new syntax

This allows them to be loaded without loading the corresponding Python
mdoule, avoiding circular dependencies.

Building Python modules through Pybind11 is a recurring task in our
Python bindings. To reduce maintainance in the build system, we introduce
a CMake function "dune_add_pybind11_module", which is semantically inspired
by the "dune_add_test" function.