Add iterateOverGrid util function

[josephwegner]

There's a ton of near copy+paste loops that look like this:

for(var q in layout.grid) {
            for (var r in layout.grid[q]) {
              var color = layout.grid[q][r].color
              if (color) {
                colorObj[color] = true
              }
            }
          }

let's just make a util function.