highspeedFFT files missing in the default branch

[mfkiwl]

Dear Tugbars,

Thanks for for your contribution; VectorFFT looks promising on its permissive license, SIMD support and speed compared against FFTW.

When I attempted to compile and test VectorFFT, my compiler complains a lot; and it seems that two main file highspeedFFT.h and highspeedFFT.c are missing. Could you please check it? By the way, I attempted to retrieve these two files from previous committement but seems to be not working.

Best regards,
Xing