Reduce header dependence on FFTW.
Initial work on CUDA support.
Working naïve interleaved interpolation with CUDA.
Implement naïve split-format interpolation using CUDA.
Complete (but untested) naïve interpolation using CUDA.
Implement CUDA padding-aware interleaved interpolation.
Destroy CUDA padding-aware plans properly.
Implement CUDA padding-aware split interpolation.
Implement CUDA padding-aware split-product interpolation.
Fix OpenMP handling in Makefile.
Make CUDA error checking nicer.
Use pinned memory for data transfers.
Simplify CUFFT error handling.
Add (inefficient) rotational transpose.
Add stubs for when nvcc is not available.
Handle return of NULL plans in benchmark.
Zero buffers to avoid no-op interpolation passing validation.