Adding DM7 signal to NEXAFS data collection

[PriyankaKetkarBNL]

I created a DM7_Photodiode_int signal in the signals.py file and added this signal to the list of signals/detectors in the energyscancore.py file.

I mainly looked for places where Beamstop_WAXS_int was used, and added the DM7_Photodiode_int signal to the list. I also saw Beamstop_WAXS_int in fly_alignment.py (fly_find_fiducials function), alignment.py (spiral scans), and common_procedures.py (buildeputable), but I did not add the DM7_Photodiode_int signal to these files, as it did not seem relevant. I also did not add the DM7_Photodiode_int signal into lines 626, 627, 636, and 637 of energyscancore.py for the same reason. Let me know if I need to adjust anything.

[EliotGann]

1. I think a more relevant user friendly name might be useful, as no one (even me a week from now) will remember what DM7 is. I might suggest changing the "name" field to be something more relevant and universally recognizable.
2. This is indeed probably very relevant to those other positions where WAXS_beamstop is being used now. in particular for alignment of fiducials (if it is a more reliable transmission signal) and building EPU tables.
3. A possible consequence of adding another signal might be a slow down in acquisitions. possibly adding some smart switching to enable and disable active signals might be something to keep in mind if we see just adding this signal changes some timing at all.

[PriyankaKetkarBNL]

I changed the signal name and propagated that throughout. I also added the large photodiode signal to the fly_find_fiducials and buildeputable functions. I still have not added it to the spiral scans, as the camera would be in the way. I plan to look into smart switching for the longer term.

[EliotGann]

Seems good. Let's try it. I'll make a issue for pairing down the signals to just those needed... I think tying it to the configuration, and adding a downstreamNEXAFS configuration is probably the way to go...