CMake: don't use CMAKE_CXX14_STANDARD_COMPILE_OPTION directly, instead go through CMAKE_CXX_STANDARD

This option is OFF by default.
If turned on cmake will notify if a target cannot be build due to a missing module.

- proper escaping of braces when passing JSON to python
- pass information if walberla was built with CUDA to pystencils
  to support apps that use GPU optionally

- information from CMake to codegen: double/float, OpenMP, ...

Michael Kuron authored 7 years ago and Christian Godenschwager committed 7 years ago

API changes in blockforest::PhantomBlockForest, blockforest::loadbalancing, pe::amr::weight_assignment
mpi can now only send/receive walberla::optional instead of boost::optional

Michael Kuron authored 7 years ago and Christian Godenschwager committed 7 years ago

API change for vtk::VTKOutput::getFilenames

External apllications which did not set the C++ standard to 14 in their CMakeLists.txt failed to build. This change allows them to build without further user actions.

- one python file can now generate multiple source files

- Add generator files to targets to show them in VS solutions
- mark generated files as such in CMake

If you have access to the old closed source waLBerla repository, you may restore the complete history with the following command
git fetch git@i10git.cs.fau.de:software/walberla.git 'refs/replace/*:refs/replace/*'