Change test_fetch_regr() to not use yield

Using yield causes the test to actually be run in the process
of collecting.  This test runs slowly (few minutes) and so even
if the test is deselected with -k it will takes the full duration
to be collected.
Update version to 0.23dev
Factor out _filter_times functionality from filter_bad_times
Add select_intervals and remove_intervals methods
Update documentation for remove/select_intervals
Update version to 0.23
Merge pull request #58 from sot/kadi-intervals

Kadi intervals