Added directory datasets, moved Nan's data in there,
and stuck in 1000 datasets generated testing the
'outlier' condition
Add dataset one_outlier

This dataset has a single large outlier at the end of Y
The rest of the points of X and Y are identical
Reorg and new class of negative AC

If you set X = (1, 2, ..., 5000) and Y = (850,850,...,850)
you get AC < 0

I added subdirs in the datasets directory