Got initial day-of-week filter working for data.
Redraws legend each time so that colors are less confusing.
Added season filter and rate filter.
Added jquery-ui slider for the year but the logic for drawing the graph
and legend needs to be cleaned up.
Core functionality and AJAX requests for different years / zones is
complete.
All persistant filters, categories, axes, zones, and years in place.
Basic styles to make active filters more apparent.