Add 'BEFORE' to target_include_directories so we include the headers
of the buildin third-party libraries before headers of third-party
libraries included in wxTOOLKIT_INCLUDE_DIRS.
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.