18.0.0

• Language standard updated to C++23.
• Old bn::hdma::start and bn::hdma::high_priority_start API deprecated.
• BN_UNREACHABLE deprecated.
• Construction of bn::string and bn::string_view from nullptr is disallowed (thanks C++23).
• bn::string::starts_with, bn::string::ends_with, bn::string_view::starts_with and bn::string_view::ends_with a nullptr char array is disallowed.
• bn::unique_ptr is now constexpr.
• bn::bitset and bn::string aren't constexpr anymore (it didn't work before).
• More overloads added to bn::string construction, assignment, bn::string::assign and bn::string::append.
• bn::string::find and bn::string_view::find added.
• bn::string::contains and bn::string_view::contains added.
• bn::string::substr added.
• bn::string_view::ends_with a char array added.
• nullptr constructor and method overloads added to bn::unique_ptr.
• Non-throwing new and delete supported.
• bn::string_view::remove_prefix and bn::string_view::remove_suffix assert fixed.
• bn::is_constant_evaluated replaced with consteval.
• Unnecessary operator!= implementations removed.
• bn::regular_bg_builder::release_map, bn::affine_bg_builder::release_map, bn::sprite_builder::release_tiles and bn::sprite_builder::release_palette ROM usage reduced.
• bn::deque iterators order operators optimized.