[Jamie, Kiwamu, Lisa]

The ETM SUS are getting kicked to the point of watchdog trips when the we lose the ALS DARM lock.  The DOWN state of the ALS_DIFF guardian was shutting off the INPUT to the LSC-DARM filter bank, but not the OUTPUT, so we were suspecting that leftover filter stuff was being driven out to the suspensions.  There are also no LSC triggers associated with the ALS error signals that could shut off the DARM output after lock loss.

I modified the ALS_DIFF DOWN state to turn off the DARM output as well, in the hopes that that would reduce the problem.  We thought that that did help, but then we just got another lock loss that did trip the ETMY SUS and ISI ST2 watchdogs, so it didn't elliminate the problem entirely.

I wonder if we'll need to add some LSC triggering based on the ALS inputs, for when we're using ALS signals to feed back to the SUS.

While I was at it, I did a bunch of code cleanup in the ALS_DIFF module.  Mostly just to keep things consistent with the guardian style guide (unpublished).  I also committed the ALS_DIFF.py module to the USERAPPS svn, and added it to the GUARD_OVERVIEW medm screen.