Fix error describing units in README file.
Play with some more clustering analyses.
Add linear model for basic predictors
Add autoregression model.

Sadly, not working yet.
Finish the autoregression model

Still doesn't work well.  Doesn't solve in optim with default options.
The way that we handle zeros in predictions or actuals is kind of
messed up.
Simplify multiple lapply calls into a single one.

No change to the output data (other than the comment attribute, which
contains the generation date).
Modify initial data processing to treat zero values as missing.