Toogle longitudinal mode automatically

[alexpron]

BIDS conversion performed by shanoir2bids.py is parameterized using template.json file.

The --longitudinal option of shanoir2bids.py call toogle BIDS session support
through the bidsSession keyword but has to be passed explicitly
even if configuration file contained a valid bidsSession key.

The idea would be to add an auto option so that the switch
between longitudinal and default mode is performed automatically depending
on if the bidsSession key is present and has a non empty value

[alexpron]

I guess this issue is about should we favor reproducibility or flexibility (usage) of the configuration file:

• reproducibility : the configuration file has to contain every option of the download, conversion and BIDS mapping (i.e.)
• flexibility : for a configuration file can we modify the behaviour of the script using command line options and retrieve the information of what has been performed using .log file

[alexpron]

A bit related to issue #23