Add helper for related boxes

[brunchboy]

For generating a series of bytes without boundaries between them on a row, something like:

(draw-related-boxes labels attr-spec)

would iterate over the labels calling draw-box for each, but overriding the attr-spec for the first, middle, and last boxes to adjust the borders.

[brunchboy]

Also add draw-boxes with the same arguments for drawing multiple boxes that are unrelated but have the same specs.