Feature request: output transfer functions at specific redshift or time value

[coccoinomane]

As Thomas put it:

I think two types of output would be nice to have: A perturbation output where the user requests perturbations output as a function of time for explicitly given triangles and a bispectrum output where the user gets all computed points in (k1,k2,k3) for given redshifts. (This would be equivalent to perturbation output and transfer output in CLASS).