SyntaxError: 'import *' not allowed with 'from .'

* use warnings module to ... raise warnings!

Make sure the output dtype of uniform is the one given as dtype parameter, and that normal Python int/float do not upcast it

That way, we use the CudaNdarray, instead of transferring back and forth
to the GPU, and the Gpu ops have CudaNdarrays as inputs, not numpy
ndarrays or scalars.