v0.4.0

• Initialize Buffer, Face, Font, FontFuncs classes in their default __cinit__ constructor; deprecate alternative create() constructors (#12).
• Avoid to copy unicode strings when populating the buffer, pass directly to hb_buffer_add_* their inner data pointers from the PEP393 canonical or shortest-representation form (#13).
• Set up test suite with support for test coverage of Cython files (#14).
• Explicitly require Python >= 3.5 in setup.py. This is required since we use PEP393 flexible unicode strings API, the typing module, etc.