When greedy word-wrap leaves a 1-word last line, pull the
penultimate line's tail word down so the orphan has at least
2 words. Skipped if the combined length would exceed budget
(invariant takes priority over cosmetics).
Visible on nested_let_rec.prose.txt:
before: '...captures outer's param\n/// i.'
after: '...captures outer's\n/// param i.'
Two new unit tests; existing 4 snapshots unaffected (none had
a 1-word orphan).
Brummel
b9e942b99d