[BUG} Conversion to JSON schema has attribute issue

[VisLab]

The conversion of a HED schema to JSON format is not handling attributes such as extensionAllowed correctly.

1. Must determine whether the problem only occurs on writing or whether it also occurs on reading in -- so that the internal representation read from the JSON is incorrect.
2. Checks show that the other schema formats handle attribute inheritance correctly.
3. The schema comparator did not detect an error -- so that also has to be corrected. It must not be checking everything when doing equivalence determinations between schemas.
4. Tests need to be augmented to insure that all attributes, not just extensionAllowed are being propagated correctly among schema formats.

[VisLab]

Fixed in PR #1160