Restructure spec line breaks

[bwiernik]

Currently, the spec is written with lines breaking at an 80 character margin (or thereabouts, didn't count). This produces a text document that is easy to read when unrendered and with line wrapping turned off in your editor, but it can make diffs harder to follow if a change includes a bunch of moving text around to avoid line breaks.

We've discussed changing to a "one proposition or idea per line" model instead. That would make diffs easier to follow.

What do you think @rmzelle ?