- checking order of integrator
- checking energy conservation
- added semi implicit euler
- improved documentation
- playground for integrator analysis

It is not needed because deprecations are compiler warnings and should not be ignored anyway.
Also, no need to export WARNING_DEPRECATED to the C++ code.

Our own wrappers was only used in one place anyway and did not all allow for specify a reason string.

DistanceComputations.h uses logging macros but does not include the
header unconditionally.

nrOfGhostLayers_ is unsigned while all cell_idx_t calculations are
signed.

If a process started by mpiexec finishes too quickly, sometimes some of the other processes are not started.
It is unclear whether this is an OpenMPI or macOS bug, but appears significantly more often since moving from macOS 10.13 to 10.15. OpenMPI 4.0.1 and 3.0.0 both show the issue on macOS 10.15.

The two-argument version was removed late in the standardization process

If load balancing changes the neighborhood, caching of receive
buffers can lead to dead locks.

Since MSVC only has beta support for OpenMP 2.0 firstprivate
cannot be used for these compilers. However, firstprivate
is necessary for a reasonably safe implementation of OpenMP
in MESA-PD. The solution is to move OpenMP support to the
generator and disable OpenMP for the checked in version.
The waLBerla OpenMP guards are removed as they are no longer
needed. It is now assumed that if MESA-PD is generated with
OpenMP support it is about to be used. If OpenMP is disabled
with CMake warnings will pop up about undefined pragmas.

Defining this function in a header without inline/static specifier may
lead to ODR violations.