Fix _event_finder() Bug

If salami slicing, the _event_finder() used to occasionally use a later
offset than was correct.
Corrected and Created Many Long _event_finder() Tests

This includes fixes to tests made necessary by the bugfix in the
previous commit.
Merge branch 'master' of github.com:crantila/vis

Conflicts:
	controllers/analyzer.py
	controllers_tests/test_analyzer.py