Enhancements to provide quarterly recurring events.
Some refactoring esp. in TemporalExpressions
Included the Nunit NUGET package in source (hope it works ...)
Enhancement for Quarterly Events

Shakinghand contribution for quarterly recurrent events.
Added yearly (anniversary) events
Merge pull request #10 from Jerry Joseph

Implements feature #2 to support recurrence on specific day of month
(e.g., the 24th of every month) as well as every "n" number of days.