Atom Date-Helpers

Adds date highlighting and conversion to Atom.

Notes

Dates accept any valid Moment.js format. Dates are slightly highlighted between the following colors along a scale (1/4th a year):

#F3B1CB, #F0ACA8, #FFC9AD, #F2E1AC, #E0F7D2, #DDEDF8, #7484DA

Caveats

• The highlights do not persist as there is currently no way to find the range of a given scope selector. When this API lands, I will fix this, otherwise we would need to build our own parser like pigments, but that is buggy.