numpy fft functions are labelled "ftt"

[kyleaoman]

This is just a minor internal housekeeping thing that I noticed: ~all of the fft functions in _array_functions.py have a shared typo fft->ftt. This is just for the internal function names and doesn't affect users (except perhaps those trying to build on top of unyt... ahem).

[neutrinoceros]

whoops. Thanks for reporting !