Start creating a new enrichSlides function.
Start creating a new enrichSlides function.

We want to progressively remove side effects in all the functions.
This commit starts with datesToGrades. It also sorts all the slices at the
beginning since it's always needed and it saves some computation in
datesToGrades as well.

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son