Remove dependency on separate extra_types.h.
Remove dependency on separate extra_types.h.

Remove the dependency on a separate extra_types.h file from the cffi wrapper and
instead just put the code inside the ffi.cdef() string.

Also, switch the string parameterization from str.format() to
Template.substitute() in order to a) keep the string definition simple (avoid
string concatenation) and b) keep the inline C code close to C (avoid "{{" and
"}}" escapes due to format()).

marcecj/faust_python