multi-ifo changes to pycbc_page_segtable

[GarethCabournDavies]

Making it so that H1 & L1 are not longer hardcoded, and that the table output now has all possible detector combinations

[tdent]

Can you post links to some tests Gareth?

[GarethCabournDavies]

Segtable with 3 IFOs and multiple rows to check:

https://ldas-jobs.ligo.caltech.edu/~gdavies/testoutput/test_segtable_output.html

I'm not sure how this will look on the actual results page though, as it is now a much wider table

Edit:
as a test of backwards-compatibilty, here is the two-ifo table:
https://ldas-jobs.ligo.caltech.edu/~gdavies/testoutput/test_segtable_output_2only.html

[tdent]

@spxiwh OK on the output from my point of view, however the functions to iterate over ifo combinations (ifo_combinations and powerset_ifos) seem like they might be more generally useful or maybe already exist somewhere - we're guessing you may know more about this

[tdent]

@spxiwh can you look at this/review briefly? the one issue I had is whether the powerset_ifos function either exists elsewhere already or belongs in a library module, eg in the workflow module ?

[GarethCabournDavies]

looking at https://ldas-jobs.ligo.caltech.edu/~gdavies/testoutput/H1L1-PAGE_SEGTABLE_VETO_SUMMARY-1187312718-428100.html in #2509 has made me want to have a look at this again at some point, need to understand if this is doing this right

I'm not sure if V1 segments are in a dfferent format and therefore need special treatment

(Fixed by 5fd82e9, see https://ldas-jobs.ligo.caltech.edu/~gdavies/testoutput/H1L1-PAGE_SEGTABLE_VETO_SUMMARY-1187312718-428100-V2.html)

[tdent]

We will ignore the powerset_ifos question (git grep powerset gives nothing) & merge when ready