Re: simplify previous patch-set by special casing 2-line staves (issue 6506090)

[Benkő Pál]

> This works, although in surprising ways.
>
> It was a challenge for me to figure out why the tests in
> 'repeat-sign.ly' come out as they do.  I was very surprised by the lines
> marked "dots in outer spaces" and "dots outside" and assume we would
> prefer more centered placement.

that's sort of all right, I meant them to surprise,
i.e. to show the limits of the implementation.
"dots in outer spaces" was inspired by your comment
http://codereview.appspot.com/6488097#msg7
"dots outside" now changed behaviour and is accordingly relabelled to
"dots in middle".  as I hinted at in
http://codereview.appspot.com/6488097#msg8
I'm afraid improving this would more than such a contorted case is worth.

> The case "dots in outer spaces" is
> different from a four-line staff in that the user indicates eight
> scale-steps will fit between lines; if eight scale steps fit legibly,
> two repeat dots will also fit.

well, we know exactly whether two dots fit or not, but the current
issue arose just from that: though they fit, the user wants them outer.
as a theoretical consideration, I think repeat sign is a matter of the
staff and the dots, not the scale steps represented by the stafflines.
(are there chromatic or microtonal notations where these steps are
smaller than a third?)

> You could simplify at this point, and work entirely in staff-positions,
> until the end where you build the stencil.  I also suggest using a rule
> "prefer dots in tight spaces to dots completely outside the staff"
> rather than the special case for 2-line staves.

that rule is implemented by patch set two.  otherwise I think this
simplification is oversimplification as it cannot distinguish

\override #'line-count = #2

from

\override #'line-count = #2
\override #'staff-space = #2

then, if staff-space is taken into account, dot size must also be, see
http://code.google.com/p/lilypond/issues/detail?id=2648
and anyway that simplification buys us no more than replacing
gap-to-find by a constant.