Barline object type ambiguity

[GeorgeTailor]

Hello,

Global measure docs mention that one of the possible children is barline, which is marked as optional, however there are instructions on how to draw barline when it is not present in the spec.

When we go to barline docs it also mentiones that type is optional, which does not make any sense, since:

1. it's the only property of this object
2. as mentioned in global measure docs it's either light-heavy or regular

IMO, specification is not a good place for logic, it should provide structure, otherwise we will end up with same problems as with MusicXML. I propose to mark barline as required in global measure object, also mark type of the barline object as required as well.

[adrianholovaty]

Thanks for the report — nicely spotted! Based on your comments, I think we need to change the following:

• Make "type" required for the barline object.
• Change the docs for the "barline" key in measure global to unambiguously refer to the barline object's type. For example, "If the measure is the last in the document, use {"type": "light-heavy"}."
• Document all allowed values for barline type. This wasn't previously done because we didn't have a way to properly document enums, but that's now possible due to a recent improvement to our docs system.