Allowed versions of the schema

[CBenghi]

Since a few implementers have started opening their solution to final users, it's critical to determine which versions of the IDS schema can be considered canonical and valid across systems, and which will not be accepted.

Until now the auditing tool was adopting a loose approach to this, in order to accept gracefully the majority of the samples in the documentation and development folders, but I've received feedback that makes it urgent to be stricter.

I hope to be able to publish an update soon, buy beyond that we need to be documenting these matters. Particularly around the expected interpretation of xsi:schemaLocation for IDS files, and the contents to be published at http://standards.buildingsmart.org/IDS.

[atomczak]

The first official version of the standard is "1.0" (https://standards.buildingsmart.org/IDS/1.0/ids.xsd). Technically and in the schema it's v1.0.0 (version="1.0.0").

All previous versions, like 0.9.7, were premature and changed with time, and I suggest to inform users that those should no longer be in use. The next anticipated version is "1.1.0".