processBIDS for MEG #231

Hi

I was trying to add an option to autoidentify BIDS meg data, to support:

aap.directory_conventions.rawdatadir = 'BIDSDir';
aap = aas_processBIDS(aap); 

My approach so far was to define megimages (i.e. meg filepaths from spm_select()) in aa_engine/aas_processBIDS.m: Branch here
Note this is very basic (i.e. I'm not trying to add events, skip/order series etc).

But I get the impression I am going about this the wrong way - megimages etc. are used as input to aap = aas_addsubject():

if toAddData
    aap = aas_addsubject(aap,subjname,mriname,...
        'structural',structuralimages,...
        'functional',functionalimages,...
        'fieldmaps',fieldmapimages,...
        'diffusion',diffusionimages,...
        'specialseries',specialimages,...
        'meg',megimages); 
end

aas_addsubject.m expects MEG data in a 1x2 cell array (ie. mri and meg filenames).
Whereas input to aas_addsubject.m from processBIDS.m is a larger cell array whose number of columns is determined by all potential modalities e.g.:

varargin =
  1×12 cell array
  Columns 1 through 4
    {'structural'}    {0×0 cell}    {'functional'}    {0×0 cell}
  Columns 5 through 8
    {'fieldmaps'}    {0×0 cell}    {'diffusion'}    {0×0 cell}
  Columns 9 through 12
    {'specialseries'}    {0×0 cell}    {'meg'}    {1×1 cell}
	). 

I guess I could make an ugly solution (e.g. if the meg filename cell ~isempty, then read those filenames for meg data) but that's not ideal.

I'll look again later, but wanted to ask if anyone could steer me at all?