Make Designer operational when an unreleased Target Platform is selected

When a set of Target Platforms is added to Studio, for example 10.X, the registries for 10.1 are manually added. Even if the user selects the 10.2 version, Modeler will use the available registry files (10.1) to operate. On the other hand, Designer won't even load if the respective registry files are missing.
Designer needs to be able to default to a previous version of the registries (if the current one is not available yet) or those registries should be provided upfront (as copies of the previous ones) and then updated when possible.