Merged in feature/add-neclib-support (pull request #368)
USE_FFT=aslfftw3 is a subset of fftw3. The setting for fftw3 should also apply to aslfftw3. Only the difference is the include file name.
USE_FFT=aslfftw3 is a subset of fftw3. The setting for fftw3 should also apply to aslfftw3. Only the difference is the include file name.