added a generalized concept for version migration of IDS files via XSLT

[MarcelStepien]

This first commit showcases a XSLT scripts for migration of IDS files defined in version 0.9.3 to version 0.9.6. This general concept of using XSLT for version migration will be recommended for handling breaking changes in future versions of IDS. All of this is maintained in a subfolder "Version migration" of the repository.

[MarcelStepien]

@CBenghi you mentioned that the files should be stored in a different folder rather then root. Can you name a folder path I should use?

[berlotti]

sorry; we cannot allow content that is not owned/copyrighted by bSI

[MarcelStepien]

@berlotti I discussed and presented this concept in the IDS development meetings. This was meant to be a first working proposal for migration using XSLT. The intention was to transfer these scripts into the hands of buildingSMART and IDS to be iterated on in the future, for example by the IDS developer meetings, once the official 1.0 version is released.

If there is still an issue regarding the origin of the script files, maybe you can add this under "Existing initiatives and proposals" or "Use-Cases"? Since there is already content included from external providers.

But I would strongly recommend to adopt the concept for future releases of the schema.