[refactor] Moved guard clauses for invalid dates from Enumerable to ScheduleEnumerator; also only adjusted seed date in comparison to schedule start/end for the direction we are enumerating (30m)
[refactor] Rewrote NeverEnumerator to be more efficient (10m)
[refactor] Overrode to_date! for Feb 29 rather than keeping the conditional (5m)
[refactor] Renamed to_date! to current_date (1m)
[skip] renamed the WeeklyEnumeratorTest file (1m)
[skip] Better to increment year by 1 rather than to overshoot a skip period (1m)
bumped version to 0.5.1