Neume information about neon

[ATranimal]

50fca0e

Preliminary work completed, information box now pops up and displays pitch information for neumes + custos.

TODO:
-Refactor into its own js file
-Somehow get clef information (ID is missing since its not a separate XML element)
-Get grouping name from verovio (hard? since its a map)

[JRegimbal]

c9964d2

By here everything is in its own file and we can get information for neumes, clefs, and custos.
We have two general functions added to vrv::Toolkit. Clef information is gotten through the staffDef tag in a bit of a roundabout way, but it doesn't seem there's a more straightforward way.

Neume grouping names are in a map local to InfoController.js as to not add a neon-specific function to verovio.

@zoemcl can you think of anything left to do for this issue?

[zoemcl]

Only thing left to do would be to display the retrieved information in a nice and consistent way but that is purely a cosmetic issue.

[JRegimbal]

Tried to make it look more like the info box in Neon.js in 0ead422.

[zoemcl]

Looks good!