Improve handling of 245$h in title display

Correct a situation where we were including the entire 245$h UNLESS
it contained specific trailing punctuation. Add comment to make
intent clearer: we omit the 245$h in (non-extended) title display,
but attempt to preserve punctuation colon, semicolon, and slash
(:;/)

Signed-off-by: Jeff Godin <jgodin@tadl.org>