SNRIFAR plots for multi-ifo file format

[tdent]

The SNRIFAR plot will need to look in various different paths/datasets to find backgrounds for the multiifo search. This could be dealt with by telling the plotting code where to look in the file (with a sensible default).

[GarethCabournDavies]

Note that this change should mean that we can use the pycbc_multiifo_add_statmap file output as well as the existing use, which will use the coinc_statmap or exclude_zerolag outputs

[tdent]

Is this still open?

[khunsang]

Sorry. Somehow I had forgotten about it. I will do it this week. Thanks for reminding.

[GarethCabournDavies]

How is this going?

[tdent]

I don't know what this was supposed to do besides produce the 'FAR vs rank' plots in the closed and open boxes, which now exist for multiifo due to a bunch of previous commits.

[GarethCabournDavies]

I wasnt sure if we were planning on making it possible to run SNRIFAR with add_statmap output, or if we did this already. If everything is good, we can close the issue

[tdent]

I don't know if that is wanted and I don't know if it has been done, so I certainly don't know if everything is good.

In any case the task, if there is one, needs a bit more definition.