Revert "FFT simply not optimized"

This reverts commit 03af2b64b72eb5580667fdcac7c2c8d1e04b0a46.
Revert "Revert "FFT simply not optimized""

This reverts commit 4e2e7e5ab43a2376ed191d43029ffd600553ba81.
Merge branch 'master' of https://github.com/ilyaDe/FFT