horizonhistory: enable doctest

gstlal-inspiral/tests/Makefile.am

 EXTRA_DIST = fixtures.py iir_pipeline_test.py itac_test_01.py test_bank.xml test_coinc.py test_skymap.py
 
-TESTS =
+TESTS = \
+	stats_horizonhistory_verify.py
 
 clean-local :
-	rm -f *.dump
-	rm -f *.avi
-	rm -f *.pyc
+	rm -vf *.avi
+	rm -vf *.dump
+	rm -vf *.log
+	rm -vf *.pyc
+	rm -vf *.trs

gstlal-inspiral/tests/stats_horizonhistory_verify.py

+#!/usr/bin/env python
+
+import doctest, sys
+from gstlal.stats import horizonhistory
+
+sys.exit(doctest.testmod(horizonhistory).failed)