Visual key signature

[craigsapp]

In this music:

The key signature on the bottom staff is incorrect (it should have no sharps/flats). This is for a B-flat clarinet, but the copyist made a mistake (probably since the previous movement has clarinets in C and this movement does not display instrument names).

Probably a good way of handling this would be to add *vk[] for a visual key signature that is displayed instead of the logical key signature (*k[]) when converting to MEI/verovio:

Also add keySig@type="visual-key-signature" when converting to MEI to allow the line:

!!!verovio: svgCss g.keySig.visual-key-signature { fill: red };

To color the visual key signature (to indicate in the score that it is an error). Test to see if the key signature @type continues on to key signatures on new systems.

Also allow tandem interpretations to be used with the sic tool. In that case the key signature should be encoded as:

*k[b-e-]
*LO:SIC:s=*
*vk[b-e-a-d-]

or

*k[b-e-]
*LO:SIC:o=*vk[b-e-a-d-]
*

Then applying sic -s would remove the visual key signature.

Full score related to this issue: http://polishscores.org/?id=pl-wtm--r-1664--004

[craigsapp]

Implemented with commit https://github.com/rism-digital/verovio/commit/56a9944bb6284e81d372b8b21e46c3b7fc2b761b

Example:

**kern  **kern  **kern
*Iclars *Ioboe  *Iflt
*ITrd1c2    *   *
*clefG2 *clefG2 *clefG2
*k[b-e-]    *k[b-e-]    *k[b-e-]
!LO:SIC:s=* !   !
*vk[b-e-a-d-]   *   *
*M3/4   *M3/4   *M3/4
=   =   =
(<8b-L 8dL  (8ddL   (8ddL
8ccJ 8e-J   8ee-J   8ee-J
=   =   =
4.dd/ 4.f/) 4.ff)   4.ff)
(<8dd 8fL>  (8ffL   8ffL
8ee- 8g 8gg 8gg
8cc 8aJ 8aaJ    8aaJ
=   =   =
4.dd 4.b-)  4.bb-)  4.bb-
*-  *-  *-
!!!RDF**kern: > = above
!!!RDF**kern: < = below
!!!verovio: svgCss g.keySig.visual-key-signature { fill: red };

Click to view MEI conversion of above Humdrum data

```xml reference RDF**kern > = above reference RDF**kern < = below reference verovio svgCss g.keySig.visual-key-signature { fill: red }; reference Xfilter sic -s Flute Oboe Clarinet in B

```

Rendering:

[craigsapp]

See also https://github.com/rism-digital/verovio/issues/3374