Force instantiating templates for abc::type_void_adapter on GCC<4.7
Add missing relational operators between abc::text::_codepoint_proxy and char32_t
Sprinkle non-ASCII characters in abc::*str test cases
Migrate abc::*str test cases to use abc::testing::utility::container_data_ptr_tracker()
Use non-BMP and non-ASCII in most abc::*str test cases