Update pyfaust.Faust ctor to handle missing Faust creation by float array list...

Update pyfaust.Faust ctor to handle missing Faust creation by float array list on GPU and secure Faust dtype consistency.

- Raising an error if a factor is not in a supported dtype (float32, double or complex128).
- Faust.dtype relies on pyx dtype function that detects the dtype directly from the core object.