Consider Removing ListTypes

[ikiril01]

It may be worthwhile to consider removing the existing *ListTypes in MAEC that serve to capture lists of individual elements, and just replacing their usage with the embedded type with a multiplicity of 0..N. This will serve to reduce the hierarchical overhead in MAEC XML instances, but it may have some unintended consequences (e.g., with JSON output), so it should be carefully considered.

[ikiril01]

This should likely be done on a case-by-case basis, as doing it globally would produce some ugly XML. One possible rule is to do it for ListTypes that encompass SimpleTypes, such as the CommentListType, in order to reduce clutter and maintain some organization around the ComplexTypes.

E.g., instead of

<Analysis>
     <Comments>
         <Comment>text</Comment>
         <Comment>other text</Comment>
    </Comments>
</Analysis>

we could have:

<Analysis>
     <Comment>text</Comment>
     <Comment>other text</Comment>
</Analysis>