Tag locklosses that occur while SEI_BS is transitioning

Checks three seconds before lockloss to see if SEI_BS was in the transitional state (-19), and tags it if that is the case. I have been assured by Jim that the SEI_BS Guardian has not been changed in several years and will not be changed in a way that would alter the -19 designation. If this is still a concern I can request the state to be assigned a permanent number.

Skips if IFO == LLO because, as far as I know, they are not having the same BS stage 2 transition locklosses that we are. Here is the tag for a lockloss from TRANSITION_BS_STAGE_2:

Closes #149 (closed)