Add proper catch2 support:
- add catch2 as a submodule
- add cmake function to add test easily
- discover each test in test binary
- remove copies of catch.hpp
- do not try to process tests for rt1051
Do not test internals of utf8, only public interface (nasty bugs could
occur otherwise).
Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>
a9cb37d7f4