TODO list for Perl module DateTime::Event::Recurrence

  - add more tests with 'interval' > 1
  - add more 'previous' tests

* find out how it behaves with mixed timezones and DST changes

* allow interleaved neg/positive values
    my $month = monthly DateTime::Event::Recurrence (
        days => [ -1, 31, 15 ],
        minutes => [ 30 ] );

* add more argument overflow tests:
  day in year, 
  week in year, 
  negative values, 
  ... 

