Ring removal error when using 16-bit floats

[aps-7bm]

I just tried to perform a reconstruction of data saved as 16-bit floats. The code was able to run successfully except for the ring removal. Both the fw and ti options gave an error in trying to convert float16 to a ctypes.

[nikitinvv]

tomopy-cli is not adapted to process everything in float16. At some processing step, the array is converted to float32 since tomopy works only with float32. I guess we should do this conversion earlier, maybe after dark-flat field correction. We can add data = data.astype('float32',copy=False) to avoid allocation of a new array for float32.

[aps-7bm]

I just added that to prep.py and did a pull request. I suppose if I was smarter I would have linked this issue to it. I tested it on one of my 16-bit float datasets and it worked fine.