Import cdfilb from scipy

Source:
https://github.com/scipy/scipy/tree/e59f9124458b64772045acbf9db7ea5a64f47044/scipy/special/cdflib
Remove python-specific error reporting
Fix missing semicolon
Compile CDFLIB and wrap it in FFI!

Woot woot. Of course the error is still just a printf,
no proper error report, nor any nice vectorization,
but at least it's callable