Feature request: create output directory for plots if it doesn't currently exist

[benkrikler]

Imported from gitlab issue 9

[eshwen]

Doesn't fix the "reverse dataset order" issue though (where the legend entries are reversed compared to the order they are given in the dataset_order list in a config)

[benkrikler]

Was that meant for this issue? They seem like unrelated features.

[eshwen]

Oops, meant for another PR

[eshwen]

i think this can be closed now