Rework the date filter and argument -- simplify some of the code but still keep as...

Rework the date filter and argument -- simplify some of the code but still keep as much flexibility as possible. You can set up the filter to provide either a date or offset selector (or both), you can set the granularity of the date parts, and any part can be set to all all values, the current time, or a specific value for either a single date or a from/to combination.