- metis: do not pass -O3 flag on msvc compiler, as this flag is ignored anyway. Instead of /w pass w0, which is equivalent to /w.
 - RheologyK17LBMKernel: A and B are also defined in D3Q27System.h. Therefore to not hide this declaration they are renamed to A_ and B_
 - additional small clean ups...

Remove debugging ls. Activate double accuracy for the numerical tests. Deactivate 256 & 512 grid sizes.

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.

no changes in configFiles for numerical tests necessary

numerical Tests of K15 and viscosity 10^-2 passes 42 of 60 tests, for the lower viscosities it has to pass 60 of 60 tests
computation time for every viscosity is ~35h on one Geforce 1080ti

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

Exchange DEPENDS (which links everything private) variable with PUBLIC_LINK and PRIVATE_LINK. Therefore VirtualFluidsCPU is linking everything public know. Everything else is still linking private.