horizon_history.py: Fix compression, so the last point is not always deleted....

horizon_history.py: Fix compression, so the last point is not always deleted. As is, the del[j:] will always delete the very last point even if there is nothing to compress. This is dangerous early on in an analysis when there are not many horizon_history points to begin with.

gstlal_inspiral: Fix verbose passage to horizon_history so compression levels print when verbose is on.

gstlal_inspiral_compress_ranking_stat: re-remove the duplicate code that had been removed by this commit but then got added back in this one seemingly by mistake. This way the bug fix will go into the single function that is used everywhere.