v1.35

Correct usage() against the options it describes

-8 said "Replaces the former -u", which documents what was rather than what is;
the rename belongs in RELEASE_NOTES.md and nowhere else. -L said "Implies -u"
and -G said "Honours -u", both naming a flag that now exits with "invalid
option -- u". And -A was described as keeping a candidate equal to its input
and an empty candidate, when it emits a MARKER in place of the absent line, and
has five of them rather than the two the text named.

The -A entry now names :SAME, :EMPTY, :REJECT, :BADRULE and :NEG, and states
the property that makes the option worth having: both engines report the same
marker for the same outcome, which is what lets a byte stream and a -8 stream be
diffed line for line.

No functional change, fprintf text only. Every option the optstring accepts now
appears in the help, and nothing appears that it does not accept.