Add IIIF for multiple editions

[craigsapp]

Plate 12021 IIIF bounding boxes have been added to the score:

https://www.digitale-sammlungen.de/en/view/bsb11108042?page=11

Plate V.A. 10 would be useful to add if there is an IIIF source for it (This is supposed to be a reprint of plage 12021, but seems like there are some differences). And probably if it is a reprint there may be corrections from plate 12021.

Here is an earlier edition that could be added as well (2nd or 3rd edition) Leipzig : Breitkopf & Härtel, [1832]
https://www.digitale-sammlungen.de/en/view/bsb11152914?page=,1

Also the "first" edition in four volumes:

https://www.digitale-sammlungen.de/en/view/bsb11137805
https://www.digitale-sammlungen.de/en/view/bsb11137806
https://www.digitale-sammlungen.de/en/view/bsb11137807
https://www.digitale-sammlungen.de/en/view/bsb11137808

[craigsapp]

Note: to see the IIIF images by system, double click on note when viewing a chorale in VHV:

https://verovio.humdrum.org/?file=chorales/chor106.krn

To view digital score in grand staff mode, use the filter satb2gs:

https://verovio.humdrum.org/?file=chorales/chor106.krn&file=satb2gs

Holding down the shift key while double-clicking on a note will display the full page that the note is on:

There is now a scan icon on the main toolbar menu that links to the online scan at the Bavarian State Library:

Which takes you to the page that the viewed chorale is on:

(Most PDF icons don't work, and maybe I will remove them).