- adds missing header to files
- unify header
- add SPDX (https://spdx.dev/) identifier to header (first step for getting REUSE https://reuse.software/ compliant)
- reworked doxgen

- uses awesome doxygen theme: https://jothepro.github.io/doxygen-awesome-css/

Adresses: #183

- adds wiki pages to doxygen page
- adds doxygen modules for production code and tests

Cp;
Higher order moments;
turbulent viscosity/intensity;
mean macroscopic values

delete scaling funcitons:
ScaleFC_comp_D3Q27F3;
ScaleCF_comp_D3Q27F3;
ScaleFC_0817_comp_27;
ScaleCF_0817_comp_27;
ScaleFC_RhoSq_3rdMom_comp_27;
ScaleCF_RhoSq_3rdMom_comp_27;
ScaleFC_AA2016_comp_27;
ScaleCF_AA2016_comp_27;
ScaleFC27;
ScaleCF27;
ScaleFCEff27;
ScaleCFEff27;
ScaleFCLast27;
ScaleCFLast27;
ScaleFCpress27;
ScaleCFpress27;
ScaleFC_Fix_comp_27;
ScaleCF_Fix_comp_27;
ScaleFC_Fix_27;
ScaleCF_Fix_27;
ScaleFC_NSPress_27;
ScaleCF_NSPress_27;
ScaleFCThS7;
ScaleCFThS7;
ScaleFCThS27_MG;
ScaleCFThS27_MG;