Hana v1.4.0 synced with Boost 1.67.0
- Added the 'take_back_c' function (#372)
- Remove the limitation on the number of members for struct macros (#376)
- Add a way to create a hana::string from a constexpr char const* (#347)
- Fix ambiguous conversion to the underlying type of integral_constants (#354)
- Bumped minimum CMake version to 3.9
- Various improvements to the CI