Fix warning: Command line warning D9025 : overriding '/W3' with '/W4'
Remove /W3, either via a regex or via new policy CMP0092 (CMake 3.15).
The policy has to be set before calling project(), otherwise the
CMAKE_<LANG>_FLAGS are already initialized.
See https://trac.wxwidgets.org/ticket/18438
Add CMake build system for libraries, tests and samples
update_files.py converts build/files into CMake format.
build/update-setup-h has been modified to update build/cmake/setup.h.in.