What this MR does / why does DuMux need it:
When building shared libraries in DuMux the libraries of upstream DUNE modules should be built as shared libraries too. Instead of automatically enabling Python bindings and setting
BUILD_SHARED_LIBS in the root
CMakeLists.txt the options should be set in
cmake.opts and used for building both DuMux and the upstream DUNE modules with dunecontrol.