An experiment to support schedules and calendar related functions in Wagn.

A Calendar card should represent the collection of cards the "match" it.  Matching means that that a search built from a number of plus cards representing parts of the date to match.  So if a Calendar card has a +year card (and no +month or +day or +day_of_week), that Calendar card would select dates in the year(s) selection, so if the value of Gerry+current_schedule+year is '2012' or '2012..2013', that would specify every day in 2012 or 2012 and 2013 respectively.

Plus cards of the form: 'YYYY_MM_DD' (or as configured via :locale feature ...) would contain the schedule for a day (with its own Cardtype if needed, but could be anything per Wagneer config).  If a given day in the Calendar's range does not exist, it should be created anytime it is needed, and this shouldn't require any special handling in Wagn.