Hervé Girod - 2022-07-20

Change the DocGeneratorAPI methods to reference to another article to point to XMLParentArticle elements rather than XMLArticle elements
Rename the getVoidArticle method as getOpaqueArticle in the DocGeneratorAPI
Fix several cases in the DocGeneratorAPI where references where not normalized, which could lead to parsing errors at resolve
Fix the alignment of table rows when some rows have custom widths
Change the addInternalMenuItem in the DocGeneratorAPI to use a XMLParentArticle rather than a XMLArticle
Fix some exceptions related to the use of OpaqueArticle elements in the DocGeneratorAPI