#4 save_mean and save_3d conflict, allocation of ws

[~Ilja]

saveing mean output depends on save_3d in namelist
when save_3d is set to .false. code silently crashes.
Seems like the problem lies in allocationing ws variable.
It is done in init_3d_ncdf when save_3d is true, but save_mean_ncdf is using the ws variable from the same init_3d_ncdf routine.
The bug appeared in getm-git source