Changes

Lscale GPUization (#1079)

* Making 2 new functions zm2zt2zm and zt2zm2zt to handle smoothing by interpolation. Replaced the spots in clubb I know that uses this to smooth things. This is just a nice to have and could allow for easy optimizations in the future by inlining the interpolations. All cases BFB on CPU and GPU, checked all relevant options too.

* GPUizing diagnose_Lscale_from_tau

* Removing some unused variables.

* Moving acc data statements from calc_Lscale_directly up to advance_clubb_core.

* Removing an unused variable.

* GPUizing the l_smooth_min_max option.

* GPUizing l_avg_Lscale

* Changes to variable names to avoid gross long names only used once.

gfortran does not like intent(out) specifiers for functions.