DataDictionary transform : merge Bitwalker XSD, or merge Bitwalker ecore models

[lfronc]

The actual transformation plugin handles subset 026-7. It is done transforming an ecore model build from bitwalker XSD to UML. This ecore model is thus specific to the subset. To handle different subsets we need to merge them.

[lfronc]

This issue seems related to issue #355.

[lfronc]

I found a better alternative (or worse depending of the point of view...) The fact is that the XSD files are generated so changing one of them would need a remerge. So instead of merging the files I try load the Bitwalker XML file using each of XSDs, and depending on the success I run the transform.