big rehaul of F_NC_S_5D for parallel computation and lower memory footprint
big rehaul of F_NC_S_5D for parallel computation and lower memory
footprint

- move init freq based on sampling to subfunction
- move population of A{} to subfunction
- set up A{} based on par (combine Nt and Nresp) or not
- rely on 'does_many' option of Gnufft, abandon GnufftSoS
- specify number of workers in each parfor

to do:
- test if do_both ~= [1 1]
- really slow in both forw/back
- huge portion of memory (85%) tied up in smaps

kickooyoo/MRI_reconstruction_tools,kickooyoo/MRI_reconstruction_tools,kickooyoo/MRI_reconstruction_tools,kickooyoo/MRI_reconstruction_tools