first pass
Generating and plot base and transformed x-value data.  However, ggplot reports missing values.  Why?
Yay, I got fits working and can plot them.  Pretty awesome.  I have not yet made use of the smoothers.  You can learn and explore a lot even without them.
Extra comment in TODO.
More on correlated data, particularly explaining the plotting results.
More intro, more applied explanation, removed and reorganized stuff to support the flow
Merge branch 'master' of github.com:jeanimal/fit_trajectory