- "if coinc_event_index" is inside "if last_coincs", which already is testing that there are coincs in the index.

This reverts commit 9159362d.

- this is to simplify changes that will be required as part of the coincidence code rewrite.  want to reduce references to last_coincs

- .from_pyvalue() now supports None

gstlal_inspiral_create_prior_diststats: remove chads mass mode file in favor of Heather's population model file

inspiral_lr: remove chads mass mode file in favor of Heather's population model file.  Additionally make sure that the iadd method can handle situations where not all objects have a population model specified, but force them to be the same if they do

- update gsl dependencies for Debian following input from Steffen.

inspiral_lr.py: remove the hardcoded 150 for horizon distance normalization and make a module level symbol