files from Python module dateutil, so we don't have to make it a mandatory import.
Include months and ANN in seasons.
Delete some print statements.
Package names may be e.g. 'amwg' or "AMWG".  Add .lower() in various places to make checks on package work.
I started trying to fix listVariables(), but gave up for now because it's a big job, and if I did it, it might
be better to start from scratch.  Anyway, my partial fixes make more things work, and do no harm.