need a serious suite of tests for ncreel

[dankamongmen]

i know that bugs exist in the ncreel implementation, because i've seen them while running growlight. we need an exhaustive suite of tests on ncreels, exercising movement (both within a full reel and a reel with free space), deletion of reels, addition of reels, and reels too large to display. keep adding tests until we've flushed some bugs out. this might be a fairly substantial effort.