Hana v1.4.0, synced with Boost 1.67.0 This release contains: - 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