Fix: remove Content column from output, because of the extra commas make it hard to read the files in.

adding wheat_group and wheat_group_display args to depo - this will be used when we start running different strains dynamically. For now we are hard-coding to "PROD". The "PROD" will appear in filenames, but not the image titles

adding function to set test outdir as an environemnt variable - so you can change the default location, which is hard-coded

making multi-year mode work

results_by_site_series
pairings_by_site_series
pairings_by_site_series_all
results_by_site_series

to use less memory