Increase required version to 3.18 and set the cmake policy CMPI0104 to NEW. Therefore the CMAKE_CUDA_ARCHITECTURES needs to be set.

Adds authors and contributing file. Clean up the readme file.
Set the minimum cmake version to 3.13 according to the readme entry.
Set the options BUILD_VF_CPU, BUILD_VF_GPU and BUILD_VF_UNIT_TEST to OFF by default.

Warning: [-Wbackslash-newline-escape]
https://stackoverflow.com/questions/31673945/clang-backslash-and-newline-separated-by-space-in-single-line-comment

Changed the setting the compiler options to the new cmake function: target_compile_options