Erronous BIDS naming.

[GalKepler]

There seems to be some small mistakes in the BIDS naming:

• I found some files ending with an "a" (i.e, ..._bolda.nii.gz). Probably due to recreating a pre-existing file using dcm2niix (that's a common behavior).
• When dealing with task/nsfMRI there should be some more specific task naming, since it is currently producing dual names (i.e, "movie-AP" etc.). The problem is that each entity separated by a "-" is considered a BIDS entity, and therefore such naming causes errors.
• It's more of a issue-tailored enhancement, but since there were few weeks where DWI were not acquired with an opposite-directed fieldmap, it could be beneficial to use same-subject, other-session fieldmap and register it to the fieldmap-missing session's DWI series.