Add root CMakeLists.txt #573

Job	Run time
macos	1h 39m 35s
mingw (MINGW64)	6h 0m 9s
mingw (MINGW32)	17m 30s
mingw (CLANG64)	1h 7m 50s
mingw (CLANG32)	1h 22m 59s
msvc (with OpenMP)	1h 15m 55s
msvc (without OpenMP)	10m 0s
ubuntu (gcc with CUDA with OpenMP)	7m 22s
ubuntu (gcc without CUDA with OpenMP)	2m 53s
ubuntu (clang with CUDA with OpenMP)	6m 27s
ubuntu (clang without CUDA with OpenMP)	3m 57s
ubuntu (gcc without CUDA without OpenMP)	2m 48s
	12h 17m 25s

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