renamed all "realfft" -> "rfft"
fixed typo in comment
ifft() is now normalized to use the same convention as numpy

as a result, ifft(fft(x)) == x is now true
added fftn flavors. These pass the transform dimension in as an argument
It's now optionally possible to use Alien::FFTW3 to find the fftw3 dependency
deleted trailing whitespace
added history and attribution to Craig DeForest to the POD, bumped version
added manifest