Refactored TimeSeries object

- No longer a global configuration for 1993
- Moved cut-off functionality into a self-contained function with an
incoming param switch (default to true) whether or not to cut off date
to lower bound (1993 currently)
The TimeRange object is pretty heavily using the "var self = this;" pattern to protect its methods from mis-scoping, but you've accidentally introduced a method that relies upon proper scoping.  This would be a lame bug to track down