Split off from qipipe v4.3.2.
Add pyxnat dependencies.
Move helpers up to module top-level directory.
Bolus arrival belongs in the pipeline.
Bump version.
Add references.
Remove cyclical dependency.
Indent method doc.
Indent method doc.
Fix doc.
Fix doc.
Fix doc.
Fix doc.
Fix doc.
Fix logging.
Add install detail.
pyxnat merged the fork, so can use official release.
Add TODO.
Revise install instructions.
Clarify comment.