Fixed periodicity issue by addind STOPPER_OUT_OF_GRID_PERIODIC flag. Further preparaions for stress BC

Add gpu options to root cmake. Add the cmake option for passing the path to the numerial tests. Add git clone test to the CI.

Change in cmake: When BUILDTYPE is not defined in vf_add_library(), a library is build regarding the CMAKE_BUILDY_TYPE.

Add a fix for the numerical tests, where all compile definitions were overwritten by set_target_properties().

Remove unused Project command in cpu.cmake and gpu.cmake

Update cmake to dev version.

Remove VirtualFluidsDefinitions.h header file.
Remove redundant compiler definitions from gpu.cmake.

Move VirtualFluids header to src.
Add CI file and add files, only existing in the open source version.

Add public target include directories to the cmake targets. Therefore the IncludeList.cmake files are not necessary anymore.
ADapt the export macros in the gks libraries.
Add 3rd/vtk helper cmake macro.
Gorup muparser into 3rd subfolder in visual studio project.

Make the cmake project more flexible while removing the CMAKE_SOURCE_DIR usage.

Make the cmake project more flexible while removing the CMAKE_SOURCE_DIR usage.

Remove unused stuff and the global include from VirtualFluidsDefinition.h. Adds missing export includes.

Renmade HOST in GridGenerator to CUDA_HOST because of a name conflict to MPI