Fleshing out api
Continuing to hack on rfc2445 stuff
RRule DSL and index creation
Expanded rrule functionality
Added time dependency in tests where necessary
Refactor occurrence => counting, add conform function
Fix time rules
Made implicit conversion Weekday=>WeekdayNum work
Added tests; more robust heuristics for doing a backward conform
index get => raw, a bit simpler
Force count to be none in Index.make