Outstanding items from foms PR

[arasskin]

13 was merged but there is still work to be done

• [x] Add vertical lines separating OSEM iterations
• [ ] Figure out how to display background variabilities
• [ ] CLI options <jaszczak> and <nema7> should probably be replaced with something like (jaszcak|nema7)
• [ ] Let's try to make the interface a bit more consistent: one of these option names turns something off, the other turns something on. It would be easier for the user to follow if they both switched something on, or both switched something off.

    --show-plot=<bool>      Display the plot generated for the FOMs [default=False]                               
    --hide-output=<bool>    Don't print results to stdout [default=False]                                         

• [ ] Do something with AOCs

[jacg]

The vertical OSEM-iterator separation (and OSEM x-axis labels) are done. I"m not entirely satisfied with the axis labels, as they look a bit messy.

Displaying background variabilities on the same graph as CRCs will be tricky, as they are approximately proportional to eachother, so they naturally interfere with eachother if placed on the same graph. SNR has the opposite trend to CRC, so they avoid eachother for the most part, and where they do interfere, they cross almost orthogonally, so there is little confusion.

[jacg]

For the CLI options issue: I'm not convinced by docopt. Perhaps click is more pleasant to use?