Save partial work on testing list events.
Fix 'insert' events for out-of-range indices.
Add tests for extend and +=
Remove redundant tests.
More tests; implement __imul__.
Merge remote-tracking branch 'origin/master' into test-list-events
Update CHANGES.txt
Merge pull request #165 from enthought/test-list-events

Implement __iadd__ and __imul__ on `TraitListObject`s.