Extension Methods from Jeff Banjavcic
Floor, Ceiling, Midpoint and Rounding calculations for various time intervals.
Calculates the next anniversary of an event after the initial date on the Gregorian calendar. Use the original event date or the event month/event day as a parameters. The optional parameter, preserveMonth will determine how to handle an event date of 2/29. Set to true will use February 28 for a standard year anniversary and set to false will use March 1 for a standard year anniversary.