a big mess, getting closer?
working: mouse. not working: buttons
extents working, transitions are ugly now
fixed extent transition
simplified transitions code
Zoom extents will be static for now

as opposed to being based on the width of the chart
Moved most helper methods outside of function binnedLineChart

Now these functions will only be generated once and behave more like a library than something part of each chart.
Cleaned up odd scale values. All but one
constants for all charts are now LIKE_THIS
organizational comments