added test code for kiss_fftnd

FFTs can now have an arbitrary # of dimensions
Also, buffer copies are eliminated.

tools/kiss_fftnd.h

@@ -0,0 +1,9 @@
+#ifndef KISS_FFTND_H
+#define KISS_FFTND_H
+
+#include "kiss_fft.h"
+
+void * kiss_fftnd_alloc(int *dims,int ndims,int inverse_fft,void*mem,size_t*lenmem);
+void kiss_fftnd(const void * cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
+
+#endif