The default target of \file is the current file.

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

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.

Moved from heat capacity to specific heat
to take into account individual mass of a particle.

To remove code duplication the distinction is now moved
into the generator. Default kernels are "with shape".

ForceTorqueNotification
HeatFluxNotification

- added ability to create custom modules