[WIP]: Charting: dates on x axis.

work in progress for #839

* extra titles -- what is show_titles for, why is it true even when there's no title in the flash chart?
* too many values on the scale (time)
* some charts still don't have dates on the x axis -- check all
* do we have some recursive Hash.update? -- use that for altering chart properties
Yeah, like these 3 lines can just be: `mri.chart.store_path(:options, :axes, :yaxis, :min, 0)`  store_path deals with creating intermediate Hashes if they don't exist.  It will also create the proper type of Hash, so if the top-most Hash is a HashWithIndifferentAccess it will create those along the way.