Chopin Mazurka: Add @sameas clefs where a clef affects multiple layers

[th-we]

I think in multi-layer situations it should be best practice to encode a <clef> in all affected layers, using @sameas to refer to a "primary" clef. This avoids having to calculate timestamps for all layers to find out what clef is active.

When used consequently, it can also be recognized when a clef is actually meant to apply to a specific single layer only, like in cross staff situations and in the well known oddity from Debussy's "La Danse de Puck":

[ahankinson]

I wonder if this is an appropriate use of @sameas. On the one hand, I can certainly see that the shape and position is the same, but on the other hand, it is a different clef.

To illustrate, would you also consider doing:

<note pname="c" dur="8" id="c8" />

and then just using <note sameas="#c8" /> for every C8 in the piece?

I don't have the answer, but I think it should be resolved, or at least discussed, before accepting this into the sample encodings.

[th-we]

I definitely agree that this needs discussion.

So you are saying that @shape and @line should be repeated? That would be in line with how the guidelines' chapter General Relationships Between Elements handles multi-layer notes. Or are you saying that @sameas shouldn't be used here at all?

[th-we]

If we agree that the attributes should be repeated, then this should also be done in Ives' "The Cage", where the double-stemmed notes are encoded like:

<note sameas="#a1"/>
<note sameas="#g1"/>
<note sameas="#f1"/>

[lpugin]

For the record, see the discussion here rism-digital/verovio#400

[rettinghaus]

@th-we if you could resolve the conflicts, I'd be happy to merge this.