versions deleted: "fft_qgradient" and "fft_qgraddot". These are the versions
of fft_gradient_r2r and fft_graddot for complex arrays with exp(iqr) behavior,
fr usage in the phonon code (gradient of Delta rho at finite q). Note that in
phonon, indices of drho_gradient have been reversed as well in vdW-DF routines,
and that the call to dgradcorr has been changed (dfftp is passed as argument)