Part of issue #48

Add fine/coarse overlap regions boundaries and fluid cells have to be setup according to the coarse grid resolution.

Vector2, Vector3 and Matrix3 define their own MPITrait::type functions that return an MPI_Datatype for them. It is created the first time the function is called and put into a static variable. It is therefore destroyed after the main() function exits, which is usually after MPI_Finalize has been called. Freeing the MPI_Datatype is therefore not possible and mpi::datatype cannot be used.

Dominik Bartuschat authored 6 years ago and Michael Kuron committed 6 years ago

unified prolongate and restrict operators to work for GCA and DCA

- NearestNeighborFieldInterpolator::get needs to break out of all loops, just not the current one. While the test seemed to succeed anyway, it crashed with corrupted memory during exit when compiled with Intel 17 in Release mode.
- FftTest should not use thread-unsafe RNG in parallel section. Otherwise the Intel 16 compiler crashes.
- Revert to -openmp on Intel < 16.0.3, which crashes while processing some of our OpenMP loops (e.g. BoundaryHandling::treatDirection).

Also adds OpenMP support for macOS (requires Xcode 7.0, CMake 3.12 and separate libomp from MacPorts/Homebrew)