sky: a lightweight UI library

examples: https://jflatow.github.io/sky

docs coming eventually, maybe

random note to self

for equal sized unit boxes
 where * :: stack, / :: grid, \ :: tile
 shape means (rows, cols)
  unit * shape = bbox
  OR
  bbox / shape = unit
  OR
  bbox \ unit = shape

so given any 2, we have all 3