Examples of cuFINUFFT usage in C++ and Python

Here we show 2D transforms of type 1 and 2, being performed, and tested,
in C++, and in Python. In each case, a batch of transforms is done with
new coefficients or weights, but the same set of nonuniform points; this
explains the suffix "many" in the code names. You may set ntransf=1 to
perform a single transform. Default options are used. In each case the
four steps (plan, setpts, execute, destroy) are used. A math test is also
performed; see the FINUFFT documentation for the definitions of the
transforms: https://finufft.readthedocs.io/en/latest/math.html

For more usage examples see:

../test/cufinufft*.cu
../python/cufinufft/tests/*.py
