title: Crossword words (across and down) storage?
body: <p>If I create a crossword puzzle, I'd want to store the words filled in on a 9 by 9 grid for example. 
  I considered a 2d array but can only store the Across words and not the Down words.
  Even if each word is stored as an object(indicating direction), I won't know which words intersect which words.
  Can someone point me in the right direction?</p>